LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 


GIFT  OK 


Class 


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QUEEN  &  CO.'S 

MANUAL 


...OF... 


Engineers  and  Surveyors 
INSTRUMENTS. 


Construction,  Manipulation,  Care,  Theory  and 
Adjustments. 


SECOND  EDITION. 


Entered  according  to  Act  of  Congress,  in  the  year  eighteen  hundred  and 

ninety-eight,  by  Queen  &  Co.,  in  the  office  of  the 

Librarian  of  Congress,  at  Washington. 


"cfo 

QUEEN  &  CO.'S 

MANUAL 


...OF... 


Engineers  and  Surveyors 
INSTRUMENTS. 


Construction,  flanipulation,  Care,  Theory  and 
Adjustments. 


Published  by 

QUEEN  &  CO.v  Incorporated, 
Philadelphia,  Pa. 
I'    S.  A. 


FIRST  EDITION, 


CONTENTS. 


Page. 

Description  of  the  Engineer's  Transit 5 

The  Manipulation  and  Care  of  the  Engineer's  Transit 19 

The  Adjustments  of  the  Engineer's  Transit 25 

The  Mathematical  Theory  of  the  Errors  of  the  Engineer's  Transit  .  37 

The  Graduated  Circles  of  the  Engineer's  Transit 59 

The  Spirit  Levels  of  Engineering  Instruments 69 

The  Telescopes  of  Engineering  Instruments 85 

Description  of  the  Engineer's  Compass  . 97 

The  Adjustments  of  the  Engineer's  Compass .    .  100 

Terrestrial  Magnetism  in  its  relation  to  Surveying  Instruments  .    .    .  105 

Description  of  the  Engineer's  Level 119 

The  Adjustments  of  the  Engineer's  Level 123 

Length  Measurements  in  Engineering 131 

Description  of  the  Plane  Table 133 

The  Adjustments  of  the  Plane  Table 135 

The  Solar  Transit 139 

The  Adjustments  of  the  Solar  Transit 142 

The  Stadia  and  The  Gradienter 147 

The  Sextant 159 

The  Barometer e 161 

The  Hand  Level 171 

The  Tape  and  Chain  .    .....,,.,. 174 

The  Leveling  Rod '177 

The  Tripod 184 


VIEW  OF  TRANSIT  PLATE. 


DESCRIPTION 

OF  THli 

ENGINEER'S  TRANSIT. 

GENERAL    INTRODUCTION. 

THE  uses  of  the  Engineer's  Transit  are  so  varied  and  con- 
venient as  to  command  for  it  the  eminent  interest  of  all 
called  upon  to  do  field  work.  Properly  designated  the  "  uni- 
versal instrument,"  the  well-made  transit  is,  above  all  others, 
the  instrument  suited  to  the  general  needs  of  the  enginee: 
As  combining  portability  with  a  high  degree  of  accuracy,  it  is 
admirably  adapted  to  the  great  majority  of  practical  problem:: 
presented  to  the  surveyor,  the  railroad  engineer,  the  mining 
engineer,  and  the  topographer.  If  of  accurate,  scientific  con- 
struction, it  may  be  relied  on  for  good  results  in  running 
straight  lines,  measuring  horizontal  or  vertical  angles,  level- 
ing, and  in  telescopically  measuring  distances. 

The  Quality  of  the  Instrument  being  a  most  important  factor 
in  good  field  work,  the  purchaser  should  have  clearly  in  mind 
the  fact  that  the  inferior  instrument  cannot  always  readily  be 
distinguished  from  the  superior,  and  that  handsome  finish,  or 
even  excellence  in  one  particular,  does  not  determine  a  good 
instrument.  The  general  excellence  of  a  transit  instrument 
depends  on  scientific  and  practical  knowledge,  on  the  part  of 
the  maker,  of  every  one  of  the  many  proper  constructive 
features,  and  on  a  conscientious  execution  of  the  task  in  every 
detail.  While  a  fine  appearance  and  rich  lacquering  are  by 
no  means  unbecoming  a  good  instrument,  there  are  in  such 
an  instrument  hidden  excellences  of  far  greater  importance. 
The  kinds  of  metal  used  in  the  various  parts  of  the  instru- 
ment, the  form  of  the  <;  centres,'*  their  truth,  the  accurate  cen- 
tering of  the  graduated  circles  and  verniers,  the  mechanical 
method  of  accomplishing  this  centering,  the  accuracy'  and 
style  of  the  graduations  of  circles  and  verniers,  the  mathe- 
matical relation  of  the  planes  of  the  graduated  circles  to  the 

5 


6  DESCRIPTION    OF    THE 

axes,  the  sensitiveness  and  position  of  the  level  tubes,  the 
form  and  position  of  the  standards,  the  relation  of  the  hori- 
zontal axis  of  the  telescope  to  the  axis  of  the  instrument,  the 
optical  and  mechanical  construction  of  the  telescope  in  gen- 
eral, the  thorough  testing  and  adjustment  of  every  mathe- 
matical, mechanical,  and  optical  characteristic  of  the  instru- 
ment, and  the  numerous  other  details  that  cannot  be  enu- 
merated, are  all,  though  often  out  of  sight,  of  essential  impor- 
tance to  a  first-class  instrument.  A  fuller  reference  to  details 
will  be  found  in  the  following  Description,  and  in  the  Special 
Articles  of  this  Manual  treating  of  the  constructive  features, 
and  of  the  theory  of  the  more  important  uses,  of  the  engineer's 
transit  and  its  accessories. 

A  Special  Test  of  Excellence  of  a  transit  instrument  is  equality 
in  the  grade  of  accuracy  possessed  by  each  essential  feature. 
It  is  not  unusual  for  makers  to  become  hobbyists  on  some 
special  feature  of  construction.  Now,  it  is  high  magnifying 
power ;  now,  professed  superiority  of  graduations  ;  and  now, 
sensitiveness  of  levels  ;  and  now,  fine  mechanical  finish.  But 
suppose,  for  example,  a  high  magnification  and  inferior  defini- 
tion and  coarse  levels  and  inaccurate  divisions,  and  is  not  the 
grade  of  work  determined  by  the  most  inaccurate  feature  ? 
The  intelligent  engineer  well  knows  that  the  transit  is  a  com- 
plex appliance  for  measurement,  and  that  every  feature  of  the 
instrument  must  be  up  to  the  standard  of  accuracy  aimed  at 
for  the  whole  instrument,  if  it  is  to  be,  in  any  true  sense,  a 
measuring  instrument.  QUEEN  &  Co.  suggest  that  the  en- 
gineer will  find  no  recreation  more  instructive  than  that  of 
testing  the  various  constructive  features  of  transits,  and  then 
computing  the  errors  which  must,  result  under  the  various  cop- 
ditions  of  use. 

The  Final  Test  of  Excellence  of  an  instrument  is  its  perform- 
ance in  skilled  hands.  Unsatisfactory  work  and  frequent  and 
expensive  repairs  put  a  ban  on  any  instrument.  But  aside 
from  the  test  in  the  field,  there  are  two  points  which  determine 
the  quality  of  the  instrument  •.  (i)  the  maker's  reliability  and 
(2)  the  maker's  knowledge  and  skill.  MESSRS.  QUEEN  &  Co. 
wish  it  understood  that  they  give  conscientious  attention  to 


ENGINEKK  S    TRANSIT.  7 

every  detail  of  construction  and  adjustment,  and  that  the  best 
scientific  talent  co-operates  with  mechanical  skill  possessing 
years  <>f  experience.  Their  experts  are  not  only  generally 
familiar  with  the  qualities  that  make  the  engineer's  transit  ef- 
ficient, but,  from  a  study  of  the  mathematical  theory  of  the 
most  accurate  uses  of  the  instrument  in  geodetic  work,  and 
from  a  broad  study  of  the  mathematical  theory  and  refined 
uses  of  all  sorts  of  instruments  of  precision,  have  attained  a 
clear  comprehension  of  the  errors  most  to  be  feared,  and 
hence,  of  the  course  of  construction  best  suited  to  secure  the 
highest  efficiency  of  the  instrument  in  the  field. 

Description  of  the  Instrument : — The  following  description  is 
intended  to  convey  some  idea  of  trie  essential  parts  of  the  tran- 
sits of  QUEEN  &  Co.,  and  of  the  purpose  of  these  parts.  It  is 
also  intended  to  direct  attention  to  the  Special  Articles,  pre- 
sented in  this  Manual,  on  the  theory,  construction,  and  uses  of 
various  parts  and  accessories  of  the  instrument. 

The  Telescope  of  the  engineer's  transit,  as  distinguished  from 
the  theodolite  proper,  is  made  to  turn  over  or  transit  at 
one  or  both  ends,  so  as  to  reverse  without  horizontal  motion. 
In  the  two  ordinary  sizes  the  telescopes  are,  respectively,  eight 
and  eleven  inches  in  length,  with  apertures  from  one  to  one 
and  one-fourth  inches  clear,  and  powers  from  eighteen  to 
twenty-five,  according  to  the  requirements  of  the  instrument. 
So  much  depending  on  the  character  of  the  telescope  for  de- 
finition, light  and  power,  and  alignment,  QUEEN  &  Co.  use  all 
the  resources  of  science  and  mechanical  art  to  bring  it  to  the 
highest  perfection.  For  further  indications  of  their  attention 
to  details,  and  for  detailed  description  of  parts,  the  reader  is 
referred  to  the  special  article  on  "  The  Telescopes  of  Engineer- 
ing Instruments" 

The  Object-Glass  and  Eye-Pieces  require  detailed  description 
and  explanation,  and  are  referred  to  at  length  in  the  article 
just  mentioned. 

A  Diagonal  Prism,  placed  immediately  in  front  of  the  eye- 
piece, so  as  to  reflect  the  rays  at  right  angles  to  the  eye,  is 
used  when  it  is  desired  to  take  vertical  angles  greater  than  it 
is  possible  to  observe  with  the  ordinary  eye-piece.  It  is  found 


8  DESCRIPTION    OF    THE 

very  convenient  for  observing  the  sun,   on  interposing   dark 
glasses  between  it  and  the  eye.  « 

The  Eye-hole  Slide  is  a  little  slide  placed  just  inside  the  eye- 
hole, and  movable  by  means  of  a  little  projecting  pin.  It  ef- 
fectually excludes  dust  and  rain  from  the  instrument,  and 
should  always  be  used  to  close  the  eye-hole  when  instrument 
is  not  in  use. 

The  Sur.-Shade  is  an  extra  piece  of  brass  tubing,  fitted  on  the 
objective  end  of  the  telescope  as  an  open  cap.  It  excludes 
direct  sunlight,  dew,  and  dust.  Its  constant  use  in  contin- 
uous work  is  insisted  on  by  some  supervising  engineers, 
with  great  advantage  to  the  quality  of  the  work. 

The  Slide-Protector  is  a  tube  screwed  to  the  objective  end  of 
the  telescope,  and  covering  completely  the  delicately  fitted 
slide  upon  which  the  object-glass  is  moved  in  and  out  for 
shorter  or  longer  sights.  It  excludes  dust  and  moisture  from 
the  slide  and  the  inside  of  telescope.  It  is  attached  to  all  of 
QUEEN  &  Co.'s  telescopes  having  the  object-glass  slide. 

The  Cross-Hairs,  placed  in  the  common  focus  of  the  object- 
glass  and  eye-piece,  are  two  fibres  of  the  little  black  field 
spider.  They  are  cemented  in  divisions  of  a  metal  ring  ac- 
curately at  90°  with  respect  to  each  other.  Platinum  wires 
are  inserted  only  on  special  order. 

The  Cross-Hair  Ring,  as  figured  in  the  accompanying  Fig,  i . 
can,  upon  release  of  its  screws, 
be  slightly  turned  for  adjusting 
one  hair  to  verticality.  By  re- 
moving the  eye-piece  and  the 
screws  of  the  ring,  the  ring  itself 
may  be  taken  out  for  the  purpose 
of  replacing  broken  wires.  This 
is  an  operation,  however,  rarely 
necessary,  and  to  be  attempted 
only  by  one  who  can  exercise 
the  requisite  care  in  replacing 
the  spider-threads  and  the  ring, 
and  also  in  placing  the  eye-piece  in  its  former  centered 
position. 


ENGINEERS    TRANSIT.  9 

The  Stadia  Hairs,  adjustable  or  fixed,  are  also  attached  to 
the  cross-hair  ring.  The  adjustable  hairs  are  attached  to 
movable  pieces,  a  a,  Fig.  I,  held  in  position  by  a  spring,  and 
can  each  be  brought  to  equal  distances  on  each  side  of  the 
fixed  thread  for  every  desired  scale  of  stadia  reading.  A  dis, 
cussion  of  the  important  subject  of  stadia  measurements  is 
given  in  the  special  article  entitled  "  Gradicntcr  and  Stadia 
Measurements" 

The  Gradienter  Screw  is  a  specially  cut  screw,  Fig.  2,  with 
graduated  head,  acting  upon  an  arm  clamping  to  the  horizontal 
axis,  for  turning  off  small  ver- 
tical angles,  and  in  the  form 
furnished  by  QUEEN  &  Co. 
affords  a  ready  means  for  run- 
ning grades  and  measuring  dis- 
tances and  differences  of  level. 
The  screw-head  reads  directly 
to  hundredths  of  a  turn  of  the 
screw,  and  is  so  placed  as  to  be 
easily  read  without  change  of 
position  of  the  observer.  One  Fis-  2- 

revolution  of  the  screw  moves  the  telescopic  sight-line  so  as 
to  intercept  one  foot  on  a  vertical  rod  at  a  distance  of  one 
hundred  feet  when  the  telescope  is  horizontal.  For  a  com- 
plete indication  of  the  advantages,  theory,  and  use  of  this 
attachment,  the  reader  is  referred  to  the  article  on  "  Gradicntcr 
and  Stadia  Measurements." 

A  Graduated  Head  for  the  Tangent  Screw  of  the  alidade  is 
sometimes  found  a  valuable  addition,  in  the  hands  of  the 
expert  engineer,  for  measuring  horizontal  angles  and  deter- 
mining distances.  Further  details,  concerning  its  use,  are 
given  in  the  article  mentioned  in  the  preceding  paragraph. 

The  Horizontal  Axis  of  the  telescope  rests  upon  the  carefully 
constructed  V's  of  the  standards,  and  is  adjustable  at  one 
end,  as  described  under  the  head  of  the  standards.  Plain 
cylindrical  pivots  are  used  where  reversal  of  the  telescope 
on  the  standards  and  the  use  of  a  striding  level  become  nec- 
essary. 


10 


DESCRIPTION    OF    THE 


The  Vertical  Arc  or  Circle,  attached  to  the  horizontal  axis 
for  measuring  angles  of  elevation  or  of  depression,  is  graduated 
to  read  to  minutes  or  less,  according  to  requirement.  The 
arc  is  sometimes  made  to  clamp  with  respect  to  any  position 
of  the  horizontal  axis,  so  as  to  permit  the  measurement  of  an 
arc  of  greater  extent  than  that  of  the  instrument.  The  com- 
plete vertical  circles  are  furnished  either  with  one  vernier  or 
with  two  opposite  verniers,  according  to  the  grade  of  work  for 
which  the  instrument  is  intended. 

The  Standards  of  the  Transit  are  made  shapely,  light,  and 
strong,  and  firmly  attached  to  the  upper  or  alidade  plate. 
The  bearing  of  the  horizontal  axis,  at  the  upper  portion  of  one 


Fig-  3- 

of  the  standards,  is  made  vertically  adjustable  by  means  of  a 
screw  and  jam  nut.  By  moving  this  bearing  up  or  down,  as 
required,  the  horizontal  axis  of  the  telescope  may  be  mao^ 
accurately  perpendicular  to  the  vertical  axis  of  the  instrument, 
as  fully  explained  in  the  articles  on  the  adjustments  and  errors 
of  the  transit. 

A  Right-Angle  Sight,  formed  by  slits  cut  in  the  two  clamping 
arms  attached  to  the  standards,  and  forming  a  means  for 
quickly  setting  off  lines  at  right  angles  to  the  telescopic  sight- 
line,  is  found  a  desirable  addition  in  some  forms  of  the  transit. 

The  Clamp-and-Tangent   Movement  attached  to  the  vertical 


KN»;i\KKK  S    TRANSIT.  II 

circle  is  a  type  of  all  clamp-and-tangent  attachments  used  in 
the  instrument,  and  may  be  readily  understood  from  the 
figured  instrument.  The  essentials  are  a  clamp  acting  with 
certainty,  a  smoothly  and  easily  moving  tangent  screw,  and  a 
stout  and  definitely  acting  spring.  The  spring  adopted  is  a 
plain,  stout  strip  of  hammered  German  silver.  QUEEN  &  Co. 
also  furnish  the  usual  enclosed  spiral  spring,  if  it  is  preferred. 
The  clamp  and  tangent  seen  immediately  above  the  upper 
plate  of  the  leveling-head,  when  in  use,  enables  the  circle- 
plate  to  be  slowly  moved  in  its  socket  in  the  leveling-head. 
The  clamp  and  tangent  as  seen  near  the  edge  of  the  alidade- 
plate,  when  in  use,  enables  the  whole  alidade,  with  telescope, 
to  be  moved  on  its  centre  with  respect  to  the  graduated  circle. 
The  form  preferred  for  this  purpose  clamps  directly  to  the 
axis  of  the  instrument,  afid  not  to  the  plate.  The  clamp-bar 
fits  snugly  on  the  axis,  and  the  clamp  acts  with  the  least  mo- 
tion of  the  screw,  and  without  strain  upon  the  circle  or  the 
least  disturbance  of  a  pointing  of  the  telescope. 

The  Alidade,  upper  plate,  or  vernier  plate,  carries  not  only 
the  verniers  but  the  magnetic  compass,  standards,  and  tele- 
scope as  well.  It  is  shown  in  the  accompanying  diagram  and 
vertical  section  of  the  instrument,  Fig.  3,  as  attached  to  the 
inner  axis  or  "  centre."  It  fs  made  as  light  as  possible,  as  is, 
indeed,  every  other  portion  of  the  instrument,  consistent  with 
the  requisite  strength  and  rigidity. 

The  Verniers  are  two  in  number,  lettered  A  and  B,  and 
placed  inside  the  graduated  circle,  and,  for  convenience  in  use, 
at  angles  of  about  30°  with  the  line  of  sight.  This  position 
of  the  verniers  enables  a  broad  and  firm  base  to  be  secured 
for  the  standards.  The  verniers  are  always  double,  having 
the  requisite  divisions  on  each  side  of  the  zero,  and  are  num- 
bered so  as  to  be  counted  in  the  same  direction  as  the  vernier 
is  moved. 

The  two  opposite  verniers  furnish  the  means   of  using  the 
well-known  principle  of  reversion  in   order  to  determine  and 
eliminate  any  outstanding  error  of  eccentricity,  to  determine 
errors  of  graduation,  and  generally  to  eliminate  errors  by  re 
version  observations. 


12  DESCRIPTION    OF    THE 

Reflectors,  of  celluloid  or  ground  glass,  are  used  to  throw 
the  requisite  light  on  the  divisions.  The  vernier  glass  covers 
are  firmly  cemented  on  the  vernier  openings,  so  as  to  exclude 
dust  and  moisture.  For  the  theory  of  the  vernier,  and  other 
points  of  interest  relating  to  reading  of  circles,  we  refer  the 
reader  to  the  special  article  on  "  Tlic  Graduated  Circles  of  tJie 
Engineer's  Transit'' 

Plain  Reading  Microscopes,  for  greater  convenience  and  ac- 
curacy in  reading  the  verniers,  are  attached  to  several  of  the 
larger  special  forms  intended  for  city,  tunnel,  or  triangulation 
work. 

Micrometer  Reading  Microscopes,  instead  of  verniers,  are 
applied  to  QUEEN  &  Co.'s  largest  and  finest  geodetic  instru- 
ments. For  description  of  this  form  of  microscope,  see  article 
entitled  "  The  Reading  Microscope — its  Forms,  Theory,  and  Ad- 
justrnents" 

Estimation  or  Scale  Microscopes  are  coming  into  use  where 
rapidity  and  a  fair  degree  of  accuracy  are  required  in  the  read- 
ings. Consult  the  article  referred  to  in  preceding  paragraph. 

The  Compass-Box,  though  not  an  absolutely  necessary  feature 
of  a  transit,  is  for  general  work  an  important  one.  It  is 
placed  between  the  standards,  directly  on  the  upper  plate.  A 
glass  cover  protects  the  compass^circle,  which  is  graduated  to 
half  degrees,  and  numbered  both  from  the  north  point  and  the 
south  point  in  each  direction,  from  o°  to  90°. 

The  Magnetic  Needle,  four  to  five  inches  in  length,  accord- 
ing to  the  size  of  the  transit,  has  at  its  centre  a  small  brass 
cap,  in  which  is  inserted  a  little  socket  of  hardened  steel,  or 
a  highly  polished  jeweled  centre,  and  by  means  of  which  the 
needle  rests  upon  the  hard,  polished  point  of  the  centre-p^n. 
It  can  thus  move  freely  in  a  horizontal  direction,  and  take  tfte 
direction  of  the  magnetic  meridian.  It  is  somewhat  weighted 
oniits  south  end  by  a  small  coil  of  fine  brass  wire,  which  can 
be  easily  moved  along  so  as  to  adjust  the  needle  to  a  truly 
horizontal  position,  or  so  as  to  prevent  dipping.  The  north 
end  is  distinguished  by  a  scallop.  The  needle  is  lifted  from 
its  pin,  when  not  in  use,  by  a  lever  actuated  by  a  screw  placed 
at  the  side  of  the  compass-box.  The  same  screw  may  be  used 


ENGINEER  S    TRANSIT.  13 

in  checking  vibrations  of  the  needle.  The  form  of  needle  pre- 
ferred is  about  six-hundredths  of  an  inch  deep  and  two- 
hundredths  wide.  The  magnetization  of  the  needle  and  other 
related  matters,  of  interest  to  practical  observers,  are  treated 
of  in  a  special  article  of  this  Manual,  entitled,  "  Terrestial 
Magnetism  in  its  Relation  to  Surveying-  Instruments." 

The  Centre-Pin  is  a  sharp-angled  cone  of  hardened  steel,  the 
point  being  made  glass  hard  and  carefully  ground.  When  the 
point  is  dull,  or  the  pin  bent,  the  pin  is  easily  removed,  ground, 
and  replaced.  On  eccentricity  of  centre-pin,  see  article  of  this 
Manual  on  "  The  Adjustments  of  the  Surveyor  s  Compass." 

The  Circle-Plate,  lower  plate,  or  limb,  as  it  is  sometimes 
called,  is  made  of  the  finest  quality  sheet  brass,  and  in  such 
manner  as  to  obviate  unequal  expansion  and  contraction 
through  temperature  changes.  The  circle  itself  is  either  grad- 
uated directly  on  the  brass,  and  then  silvered,  or  upon  a  rim 
of  silver  securely  set  into  the  plate.  In  the  production  of  an 
accurate  graduated  circle,  there  are  two  points  of  especial  im- 
portance :  First,  the  character  of  the  graduation,  and,  secondly, 
the  centering  of  the  circle  with  respect  to  the  axis  of  the  in- 
strument. With  the  facilities  possessed  by  QUEEN  &  Co.  for 
producing  finely  graduated  circles  for  astronomical  and  en- 
gineering instruments,  no  errors  of  graduation  need  be  feared, 
but  the  graduation  itself  may  be  relied  on  with  the  utmost 
confidence.  For  a  further  description  and  discussion  of  the 
graduations,  we  refer  the  reader  to  a  special  article,  entitled 
"  The  Graduated  Circles  of  the  Engineer  s  Transit."  The  cen- 
tering of  the  circle  is  provided  for  by  special  devices  which 
not  only  allow  it  to  be  accomplished  with  certainty  and  ac- 
curacy, but  also  to  be  maintained  after  the  adjustment  has 
once  been  made.  For  a  discussion  of  the  subject  of  eccen- 
tricity, we  refer  the  reader  to  a  special  article  of  this  Manual, 
entitled  :  "  The  Errors  of  Eccentricity  of  the  Engineer  s  Tran- 
sit:' 

The  Graduations  are  made  with  fine,  uniform,  dark  lines,  so 
as  at  the  same  time  to  be  read  with  ease  and  accuracy.  The 
numbering  is  usually  from  o°  to  180°,  in  two  directions,  with 
a  second  numbering  on  half  of  the  circle,  round  to  360°. 


14  DESCRIPTION    OF    THE 

Thus  angles  may,  with  facility  and  certainty,  be  read  in  any 
manner  desired.  A  very  convenient  set  of  inclined  numbers 
has  been  adopted  on  the  circle  ;  the  inclination  always  indi- 
cating in  what  direction  from  the  zero  the  reading  is  being 
made.  Hence,  with  the  kind  of  numbering  adopted,  and  with 
the  inclined  figures,  the  engineer  always  has  a  sure  method 
of  remembering  the  direction  of  the  angle  measured.  The 
sizes  of  the  circles  vary,  usually,  from  five  and  one-half 
inches  to  six  and  one-half  inches  diameter.  They  are  grad- 
uated, ordinarily,  to  half  degrees,  and  read  to  minutes,  or,  in 
order  to  give  wider  space  on  the  vernier,  to  twenty  minutes 
and  read  to  degrees,  or  to  twenty  minutes  and  read  to  thirty 
seconds,  or,  in  the  higher  grades,  to  any  required  fineness  of 
reading. 


Fig.  4. 

The  Vertical  Axis  of  the  transit,  as  shown  in  section  in  the 
accompanying  Fig.  4,  is  determined  by  two  concentric 
conical  "  centres,"  as  they  are  called.  The  vernier,  or  alidade- 
plate,  is  attached  to  the  inner  "  centre,"  and  the  graduated 
circle  is  attached  to  the  outer  "  centre,"  which,  in  turn,  fits 
into  the  socket  of  the  leveling-head.  It  is  of  the  highest  im- 
portance that  these  "  centres  "  should  be  turned  and  fitted  with 
mathematical  accuracy,  and  to  insure  this  QUEEN  &  Co.  turn 
both  "  centres  "  finally  on  the  lathe  between  dead  centres. 


ENGINEERS    TRANSIT.  15 

The  surfaces  of  the  "  centres "  do  not  come  in  contact 
throughout  their  entire  length,  but  are,  for  about  one-third 
the  distance,  cut  away,  so  as  to  insure  a  positive  mathematical 
axis  under  all  conditions  of  wear.  Not  only  should  the  axis, 
when  the  instrument  is  sent  out,  be  exactly  concentric  with  the 
centre  of  the  graduated  circle,but  it  should  have  been  so  designed 
as  not  to  introduce  the  error  of  eccentricity  by  wear.  It  has, 
however,  been  found  that,  in  some  patterns  of  "  centres,"  wear 
not  only  produces  the  error  of  eccentricity,  but  introduces 
it  in  such  form  as  to  be  irremediable  without  the  construction 
of  new  centres. 

In  order  to  prevent  unnecessary  wear,  and  lessen  friction, 
the  three  metals  of  the  inner  "  centre,"  the  outer  "  centre," 
and  the  leveling-head  socket  are  selected,  not  only  with  a 
view  to  the  requisite  rigidity,  but  with  a  view  to  a  small  rel- 
ative co-efficient  of  friction.  Bell-metal,  of  the  hardest 
quality,  should  be  used  for  the  inner  "  centre,"  a  fine  gun- 
metal  for  the  outer  "  centre,"  and  a  superior  quality  of  red 
metal  for  the  socket  of  the  leveling-head.  MESSRS.  QUEEN 
&  Co.  having  in  their  own  establishment  superior  facilities  for 
making  the  necessary  castings,  are  enabled  to  compound  alloys 
of  metals  with  a  special  view  to  the  theoretical  conditions  in 
important  pieces,  such  as  the  "  centres  "  and  their  sockets. 

The  Levels  of  the  Transit  are  usually  three  in  number.  Two 
are  attached  at  right  angles  to  each  other  on  the  upper  plate 
or  alidade,  one  being  parallel  to  the  line  of  sight,  the  other 
transverse  to  it.  Various  positions  are  given  to  these  levels 
on  the  alidade  by  makers,  according  to  the  different  con- 
structive demands  ;  and  the  positions  assigned  are,  indeed, 
quite  indifferent,  if  the  levels  are  in  proper  relation  to  the  line 
of  sight  and  easily  adjustable.  For  adjustment  of  these  plate 
levels,  with  respect  to  the  vertical  axis  of  the  instrument, 
proper  screws  are  provided,  and  care  should  always  be  taken 
to  unloosen  the  little  clamping  screws  at  the  ends  of  the  bubble- 
cases  before,  and  to  tighten  them  after,  moving  the  vertical 
adjusting-screws. 

The  third  level  is  the  fine  one  attached  to  the  telescope- 
tube,  parallel  to  the  line  of  sight.  Sometimes  a  highly  sensi- 


1 6  DESCRIPTION    OF    THE 

tive  striding-level  is  furnished,  for  leveling  the  horizontal  axis, 
in  the  higher  grades  of  instruments.  And  sometimes,  also,  a 
coarse  circular  level  is  attached  to  the  alidade  for  quick  level- 
ing. The  solar  and  other  attachments  often  have  their  own 
proper  levels. 

The  transits  of  QUEEN  &  Co.  are  furnished  with  accurately 
designed,  carefully  made  levels,  true  and  suitably  sensitive, 
and  each  level,  including  the  plate-levels,  provided  with  di- 
visions throughout  its  entire  length,  so  as  to  allow  of  accurate 
use  under  all  conditions.  The  importance  of  the  level  as  a 
constructive  feature,  and  its  general  theory  and  use,  are 
treated  of  in  a  special  article  of  this  Manual  entitled:  "The 
Spirit  Levels  of  Engineering  Instruments" 

The  Leveling-Head  is  shown  in  the  lower  part  of  the  ac- 
'companying  Fig.  3,  giving  a  vertical  section  through  the  plates 
and  centres.  It  consists,  essentially,  of  the  two  leveling-plates 
and  leveling-screws.  In  these  long-centre  transits,  the  level- 
ing-head  is  not,  as  in  some  inferior  short-centre  instruments, 
removable,  but  at  all  times  forms  an  essential  part  of  the  in- 
strument. It  need  scarcely  be  remarked  that  in  all  high-grade 
long-centre  instruments  it  is  not  removable,  for  the  reason  that 
only  thus  can  the  most  accurate  adjustments  be  attained  and 
kept,  at  the  same  time  that  the  centres  are  protected  from  irre- 
trievable injury.  QUEEN  &  Co.  have  found  that  the  short- 
centre  instruments,  with  removable  head,  are  those  most  fre- 
quently coming  in  for  repairs.  Leveling-heads  with  four 
leveling-screws  are  those  usually  preferred  by  American  en- 
gineers ;  bf v!.,  upon  special  order,  heads  with  three  leveling- 
screws  arc  also  supplied.  The  screws  are  all  covered  with 
neat  dust-caps,  and  provided  with  milled  heads  of  moderate 
diameter,  those  of  very  large  diameter  having  been  found  to 
give  too  much  mechanical  advantage  to  inexperienced  and 
thoughtless  users,  and  also  to  impede  quick  leveling.  The 
leveling-head  is  attached  to  the  tripod-plate,  either  by  means 
of  a  neat  and  effective  clamp,  or  by  means  of  screw,  as  pre- 
ferred by  the  engineer.  The  clamping  device  saves  a  little 
time  in  setting  up  and  dismounting  the  instrument. 

The  Shifting-Centre,  as  now  supplied  with  each  of  the  QUEEN 


ENGINEER'S  TRANSIT.  17- 

&  Co.  transits,  allows  the  vertical  axis,  with  its  attached 
plumb-line  and  bob,  to  be  accurately  brought  over  a  desired 
point,  when  once  the  instrument  has  been  approximately  set 
up  over  the  point.  With  the  leveling-screws  somewhat 
loosened,  the  whole  instrument  may  be  freely  moved  on  the 
lower  level-plate  to  any  required  position.  The  great  amount 
of  time  saved,  and  the  accuracy  attained  in  setting  up  by 
its  means,  makes  the  shifting-centre  invaluable  to  the  en- 
gineer. 

The  Quick-Leveling  Attachment  consists  of  wedge-like  rings, 
which,  as  a  separate  piece,  is  clamped  or  screwed  directly  on 
the  tripod-plate.  The  instrument  is  then  clamped  or  screwed 
upon  the  attachment,  and,  by  an  easy  revolution  of  the  rings, 
quickly  brought  to  an  approximately  level  position.  The  fine 
leveling  is  then  accomplished  by  the  leveling-screws.  It  is 
furnished  only  upon  special  order. 

The  Tripod,  furnished  with  QUEEN  &  Co.'s  instruments,  is 
designed  to  be  rigid,  of  moderate  weight,  and  adjustable  to 
position  with  ease  and  certainty.  Fine  white  ash-wood  is 
used  for  the  legs,  as  supplying  the  requisites  of  strength  and 
lightness.  The  legs  are  furnished  with  a  sharp  steel  shoe, 
well  fitted  to  the  wood.  Winged  clamping-screws  are  used  to 
fasten  the  legs  to  the  plate.  The  forms  supplied  are  (i)  the 
ordinary  round  leg  of  elegant  pattern,  (2)  an  improved  "  split- 
leg  "  tripod,  and  (3)  an  excellent  extension  tripod. 

The  Plumb-Bob  is  accurately  attached  to  the  central  axis  of 
the  instrument  by  means  of  a  small  hook  and  chain,  and  is  in 
all  cases  made  adjustable.  It  is  supplied  in  any  desired  weight, 
from  eight  ounces  up  to  the  heavy  ones  of  two  and  three 
pounds  required  for  plumbing  down  deep  shafts.  They  are 
usually  made  of  brass,  and  steel  pointed. 

The  Plummet-Lamp,  supplied  for  mining  and  other  purposes, 
is  so  arranged  that  either  the  oil  light  or  a  small  incandescent 
electric  lamp  can  be  used.  The  small  incandescent  lamp 
is  attached  centrally  on  the  cap  which  covers  the  wick  of 
the  oil  lamp  when  the  latter  is  not  in  use.  A  small  storage 
battery,  or  several  cells  of  some  suitable  battery,  will  furnish 
the  electrical  energy  required.  The  wires  running  to  the 


1 8  DESCRIPTION    OF    THE    ENGINEER'S    TRANSIT. 

incandescent  lamp  are  perfectly  flexible,  and  a  key  is  inserted 
in  the  circuit,  so  as  to  enable  the  lamp  to  be  lit  and  ex- 
tinguished rapidly  for  purposes  of  signaling.  The  entire 
steadiness,  certainty,  and  safety  of  the  electric  lamp  under  all 
conditions  in  mining  have  induced  QUEEN  &  Co.  to  fit  the 
lamp  also  to  targets  of  the  leveling-rod,  so  as  to  permit  the 
ready  use  of  the  gradienter-screw  and  stadia  wires  in  under- 
ground or  night  work. 

The  Solar  Attachment,  for  determining  the  true  meridian,  is 
readily  fitted  to  any  form  of  transit,  but  for  the  most  trust- 
worthy results  requires  to  be  fitted  only  to  transits  capable  of 
meeting  the  mathematical  requirements.  For  a  full  descrip- 
tion of  the  attachment,  its  theory,  and  use,  the  reader  is  re- 
ferred to  the  article  of  this  Manual  on  "  The  Solar  Transit,  and 
Methods  of  Determining  the  Astronomical  Meridian." 

The  Forms  of  the  Transit  made  by  QUEEN  &  Co.  range  from 
the  plain  transit,  without  telescope,  level,  or  vertical  arc,  to 
the  large  altazimuths  of  refined  construction,  intended  for 
geodetic  triangulation  and  astronomical  field  work.  Some  of 
these  forms  are  more  particularly  described  and  figured  in 
their  Catalog-tee  of  Engineers'  and  Surveyors'1  Instruments, 
and  the  reader  is  also  referred  to  their  Catalogue  of 
Astronomical  Instruments  for  information  relative  to  in- 
struments made  by  them  for  astronomical  observations. 
Popular  forms  of  the  transit  are  the  complete  engineer's  tran- 
sit, with  either  six  and  a  half-inch  circle  and  five-inch  needle, 
or  with  six-inch  circle  and  four  and  a  half-inch  needle ;  the 
light  mountain  transit,  with  five  and  a  half-inch  circle  and  four- 
inch  needle ;  and  a  cheaper  grade  of  engineer's  transit,  with 
four  and  a  half-inch  circle  and  five-inch  needle.  In  addition 
to  instruments  of  the  usual  weight,  QUEEN  &  Co.  also  make 
transits  in  which  the  metal  used  is,  for  the  most  part,  alum- 
inum, and  the  weight  reduced  to  a  minimum. 


QUEEN"  TRANSIT  THEODOLITE. 


A  1470. 


Price,  $850.00 


THE  MANIPULATION  AND  CARE 

OF  THE 

ENGINEER'S  TRANSIT. 


TO  Set  Up  the  Transit  on  nearly  level  ground,  stretch  out 
one  leg  of  the  instrument  and  set  it  loosely  at  a  con- 
venient distance  from  the  point  over  which  the  instru- 
ment is  to  be  placed.  This  distance  should  be  so  taken  that 
the  legs  of  the  transit  will  make  angles  of  between  50°  and 
60°  with  the  ground.  Now  spread  out  the  other  two  legs  and 
plant  them  in  the  ground  so  that  the  distances  of  each  leg 
from  the  point  will  be  nearly  equal.  Next,  press  on  each  of 
the  three  legs  successively  so  as  to  drive  them  firmly  into  the 
ground.  If  the  ground  be  hard  very  slight  pressure  will 
suffice.  The  distance  to  which  each  leg  is  driven  into  the 
ground  should  be  so  regulated  as  to  bring  the  bob  approxi- 
mately over  the  required  point.  The  bob  may  now  be  brought 
accurately  over  the  point  by  unloosening  the  plate-screws  and 
sliding  the  shifting  centre.  Then  level  both  ways,  taking  care 
to  tighten  fairly  but  not  to  strain  the  leveling  screws,  and  the 
instrument  is  ready  for  work. 

A  good  surveyor  will  always  endeavor  to  arrange  his  instru- 
ment in  setting  up  so  that  the  height  of  the  eye-piece  \vill 
nearly  coincide  with  the  height  of  his  eye  when  standing  erect. 
This  will  avoid  a  cramped  position  in  taking  sights.  Judg- 
ment must  be  used  in  the  case  of  a  tall  person,  to  prevent  an 
insecure  position  of  the  instrument,  such  as  would  be  caused 
by  having  the  legs  too  close  together. 

When  setting  up  the  instrument  on  ground  of  any  slope 
whatever,  one  leg  of  the  instrument  should  be  placed  on  the 
slope  above  the  point,  the  other  two  remaining  below.  A 
rough  estimate  should  be  made  so  that  the  upper  leg  may  be 
brought  further  distant  from  the  point  than  the  other  two, 
whose  distances  from  the  point  should  be  nearly  equal.  The 

19 


20  MANIPULATION    AND    CARE    OF    THE 

excess  of  distance  of  the  upper  leg  over  that  of  the  other  two 
must  be  greater  as  the  slope  is  more  inclined.  It  is  advisable 
first  to  push  the  upper  leg  into  the  embankment  as  far  as  pos- 
sible, and  then  to  press  in  the  other  legs  until  a  secure  posi- 
tion is  obtained.  This  method  will  bring  the  screw-plate  more 
nearly  level. 

In  the  case  of  setting  up  over  a  point  on  the  edge  of  a  per- 
pendicular cut,  one  leg  should  be  driven  into  the  side  of  the 
cut,  the  others  being  spread  out  over  the  top. 

Shouldering,  carrying,  and  setting  up  an  instrument  requires 
practice  and  artistic  method  to  avoid  accidents  and  inconveni- 
ence. In  taking  the  instrument  up,  first  see  that  the  lower 
clamp  is  loosened,  and  always  leave  it  moderately  loosened 
when  the  instrument  is  not  in  actual  active  use.  Next  bring 
one  shoulder  squarely  against  one  leg  near  the  tripod  head, 
and  rest  the  instrument  against  the  shoulder  while  the  instru- 
ment is  turned  upon  this  tripod  leg  as  a  pivot,  and  the  other 
two  are  successively  folded  in  toward  it.  Now  take  up  the 
instrument  and  balance  on  the  shoulder.  In  setting  up,  re- 
verse the  process  by  first  resting  the  instrument  on  one  leg 
and  turning  the  instrument  upon  its  toe  as  a  pivot,  successively 
bring  the  other  two  legs  into  position,  as  indicated  in  the  pre- 
ceding paragraph. 

Grasp  the  Instrument,  in  mounting  and  dismounting  from 
tripod,  always  by  the  leveling  head  only.  When  the  instru- 
ment is  not  in  use,  or  not  being  carried,  leave  the  leveling 
screws  and  the  lower  clamp  only  slightly  clamped. 

The  Tripod  Legs  should  always  have  their  shoes  sharp  and 
tightly  screwed  to  the  wood.  The  legs  should  also  be 
snugly  clamped  to  the  tripod  head. 

The  Leveling  Screws  should  all  be  fairly  seated  before  af 
any  time  removing  the  instrument.  If  leveling  screws  or  tan- 
gent screws  work  hard,  clean  the  threads  well  by  means  of  a 
small,  stiff  brush  and  a  little  oil,  taking  care  finally  to  remove 
all  oil.  Overstraining  of  any  and  all  screws  should  be 
avoided. 

The  Magnetic  Needle  should  always  be  very  gently  set  free 
upon  the  centre  pin,  so  as  not  to  dull  the  pivot ;  and  the  needle 


ENGINEER'S    TRANSIT. 


21 


should  also  always  be  arrested  and  screwed  fairly  against  the 
glass  cover  before  moving,  carrying,  or  dismounting  the  instru- 
ment. Wide  vibrations  of  the  needle  may  be  gently  checked 
by  means  of  the  needle-lifter.  The  glass  cover  of  the  com- 
pass-box should  be  wiped  off  only  with  linen,  and  then  gently 
breathed  on  to  relieve  all  electrification  produced  by  rubbing. 
Iron,  as  disturbing  the  needle,  should  be  carefully  excluded 
from  hat  rims,  buttons,  watch  chains,  reading-glasses,  specta- 
cles, and  the  like.  On  placing  the  instrument  away  after  use, 
first  release  the  needle,  and  then,  after  it  has  taken  up  the  di- 
rection of  the  magnetic  meridian,  raise  it  against  the  glass. 
No  false  deflection,  due  to  magnetization  of  the  metals  used  in 
the  instrument  need  be  feared,  since  QUEEN  &  Co.  take  special 
precautions  to  carefully  test  all  metals  entering  into  the  con- 
struction of  the  instrument,  and  reject  any  piece  giving  the 
slightest  indication  of  magnetic  properties. 

The  Spirit  Levels,  in  proportion  to  their  sensitiveness,  are 
liable  to  error  from  differences  of  temperature  in  their  parts. 
They  should  not  be  touched,  or  exposed  to  any  sudden 
changes  of  temperature.  The  bubble  will  invariably  move 
toward  the  end  having  the  higher  temperature.  Accuracy  re- 
quires a  carefully  preserved,  even  temperature.  For  faults  of 
levels,  consult  the  article  of  this  Manual  on  "  The  Spirit  Levels 
of  Engineering  Instruments" 

The  Focusing  upon  the  hairs  is  accomplished  by  carefully 
turning  the  eye-piece  like  the  nut  of  a  screw,  until  the  hairs 
appear  most  sharply  defined.  The  focusing  upon  the  object  is 
accomplished  by  gently  turning  the  milled  head  near  the 
objective  end,  until  the  object  appears  most  clearly  defined  in 
the  telescope.  Consult  the  paragraph  under  the  same  heading, 
in  the  article  of  this  Manual  on  "The  Telescopes  of  Engineering 
Instruments" 

The  Sun  Shade  should  be  used  as  much  as  possible,  as  it  is 
nearly  always  an  advantage  to  good  work,  as  well  as  to  the 
protection  of  the  instrument. 

The  Cross-Hairs  may  be  relieved  of  any  annoying  dust  par- 
ticles that  cling  to  them  by  removing  the  eye-piece  and  very 
gently  blowing  into  the  tube.  Broken  cross-wires  may  be  re- 


22  MANIPULATION    AND    CARE    OF    THE 

placed  by  an  engineer  accustomed  to  nice  manipulation  and 
patience,  as  follows :  Provide  a  little  shellac,  dissolved  in  the 
best  alcohol,  a  small,  fine  camel's-hair  brush,  and  a  U-shaped 
frame  upon  which  has  been  previously  spun  off  a  continuous 
thread  from  a  little  black  field  spider,  the  thread  best  adapted 
to  varying  hygrometric  conditions.  Removing  the  cross-hair 
ring  and  carefully  cleaning  it  with  alcohol,  place  it  on  a  table, 
with  the  graduated  lines,  intended  to  receive  the  threads, 
uppermost.  Then  carefully  lay  the  U-frame  on  it,  in  such  a 
manner  as  to  bring  one  fibre  approximately  in  coincidence  with 
a  division.  Brush  it  gently  into  the  division,  and  fasten  at  one 
end  with  a  drop  of  shellac.  Wait  a  minute  for  this  to  harden, 
and  then  stretch  the  fibre  across  and  secure  it  in  the  division 
at  the  other  end  by  means  of  a  little  shellac.  After  waiting, 
as  before,  for  it  to  harden,  remove  all  extraneous  fibres,  and 
proceed  in  like  manner  to  insert  the  other  thread  at  right 
angles  to  the  thread  already  fastened. 

The  Cleaning  of  the  Lenses  of  a  telescope  should  always  be 
undertaken  with  caution.  The  fine  polish  of  the  lenses  of 
first-class  instruments,  so  necessary  to  the  transmission  of  a 
high  percentage  of  the  light,  is  attained  only  by  the  use  of  the 
most  delicate  processes  of  the  optician's  art.  And  it  would  be 
most  unfortunate  if,  from  ignorance  or  carelessness,  the  highly 
transparent  glasses  should  be  dulled  forever  by  a  clumsy  wip- 
ing. Therefore,  as  a  precaution,  do  not  unnecessarily  attempt 
to  clean  them.  Particularly  do  not  add  the  insult  of  grease  to 
the  injury  of  dirt,  by  dabbing  your  fingers  against  the  surfaces 
of  the  glasses. 

If  dust  is  found  upon  the  lenses,  gently  brush  it  off  with  a 
fine  camel's-hair  brush.  If  dirt  still  clings,  slightly  moisten 
the  lens  by  breathing  upon  it ;  then,  take  a  piece  of  very  old 
and  very  fine  linen,  and  so  wipe  off  the  dirt  as  continually  to 
push  the  dirt  in  front  of  the  linen.  Do  not  roll  the  dirt  parti- 
cles under  the  linen,  and  then  scratch  the  glass  by  pressure 
and  rubbing.  Silk  and  buckskin  are  objectionable ;  the  for- 
mer scratches,  and  the  latter  often  contains  gritty  particles. 
Keep  a  piece  of  fine  old  linen  in  your  box,  and  use  that  only. 
Moistening  the  lens  with  a  little  alcohol  will  sometimes  be  de- 


ENGINEERS    TRANSIT.  23 

sirable,  in  order  to  restore  the  original  brilliancy  of  the  sur- 
faces. Keep  the  outer  surfaces  of  eye-piece  and  object-glass 
always  free  from  dust,  moisture,  and  grease  by  careful  cleaning, 
as  here  indicated. 

Moisture  penetrating  between  the  crown  and  flint  lenses  of 
the  objective,  after  exposure  of  the  instrument  in  rain,  will  be- 
come visible  there  as  a  mist  obscuring  the  view. ;.  Since  the 
lenses  of  the  objective  should  never  be  separated,  it  is  in  such 
cases  necessary  to  place  the  instrument  in  a  warm  room  until 
the  moisture  has  been  thoroughly  evaporated,  or,  if  this  does 
not  prove  successful,  carefully  unscrew  the  objective  and  ex- 
pose it  to  a  gentle  heat ;  but  do  not,  in  any  case,  remove  the 
lenses  from  their  cell.  If  at  any  time  it  becomes  necessary  to 
dry  out  the  interior  of  the  tube,  the  eye-piece  may  be  re- 
moved and  the  eye-end  carefully  covered  with  a  fine  clean 
piece  of  linen  to  exclude  dust. 

The  Object  Slide,  notwithstanding  the  nicely  fitted  slide- 
protector,  may  in  time  grind  or  work  hard.  The  slide  is  ex- 
posed by  unscrewing  the  protector,  and,  if  necessary,  also  the 
pinion  head  which  moves  the  objective.  Careful  cleaning  is 
usually  all  that  should  be  attempted.  Oil  gathers  and  holds 
dust.  If  the  object-slide  begins  to  fret,  examine  it  instantly. 

The  Centres  and  Graduation  are  exposed,  and  the  main 
body  of  the  instrument  taken  apart  by  unscrewing  in  turn  the 
upper  clamp,  the  dust-cover  ring  which  embraces  the  lower 
plate,  and,  finally,  the  centre  screw  from  which  the  plummet 
hangs.  The  graduations  are  first  to  be  brushed  with  extreme 
care  with  a  camel's-hair  brush,  and  then,  if  necessary,  wiped, 
but  only  at  right  angles  to  the  divisions,  and  never  rubbed, 
especially  not  on  the  edge.  The  centres,  when  clean,  may  be 
slightly  lubricated  with  pure  watch  oil.  It  is  to  be  clearK 
understood  that  only  after  years  of  use  should  it  be  necessary, 
and  therefore  desirable,  to  separate  the  centres  for  inspection 
and  cleaning  of  the  interior  parts.  QUEEN  &  Co.  use  every 
artifice  and  precaution  which  good  design  and  fine  workman- 
ship can  provide  for  excluding  dust  and  moisture  from  the 
instrument,  and  therefore  only  after  long  continued  rough 
usage  should  an  examination  of  the  centres  be  necessary.  If 


24  MANIPULATION    AND    CARE   OF    THE, 

the  centres  fail  to  revolve  with  the  usual  freedom  after  expos- 
ure in  extremely  cold  or  hot  weather,  take  an  early  oppor- 
tunity to  inspect  them.  If  the  centres  begin  to  fret,  examine 
them  instantly. 

The  protection  of  the  instrument  from  rain,  dust,  and  con- 
tinued exposure  to  the  direct  rays  of  the  sun  are  a  constant 
'duty  and  difficulty.  The  white,  cashmere-lined  gossamer  rub- 
ber cover  furnished  by  QUEEN  &  Co.  with  their  transits,  and 
always  to  be  carried  with  the  instrument,  is,  as  a  rain-proof, 
dust-proof,  and  heat-proof  protector,  of  great  practical  advan- 
tage. Carelessness  in  exposing  the  instrument  to  the  curiosity 
of  cattle,  or  to  other  unnecessary  risk,  and  in  general,  an  un- 
couthness  of  usage,  indicate  such  lack  of  respect  for  skilled 
and  conscientious  workmanship  as  to  be  quite  unpardonable. 

The  Instrument  Box  should  always  be  used  in  transporting 
the  instrument.  QUEEN  &  Co.'s  boxes  are  all  provided  with 
flexible  rubber  cushions  for  taking  up  the  sudden  jars  or  vio- 
lent vibrations  incident  to  travel. 

The  Manipulation  in  general  should  possess  "  an  ease  and 
smoothness  "  that  makes  it  next  to  impossible  on  the  one  hand 
to  give  a  good  instrument  a  disposition  to  fret  in  any  of  its 
parts,  or,  on  the  other  hand,  to  bring  about  serious  injury  in 
an  instrument  whose  parts  need  careful  cleaning  or  have  been 
bent  and  strained  by  a  fall. 

Repairs  become  necessary  to  the  best  instrument  in  time, 
and  should  not,  when  really  needed,  be  unduly  postponed. 
QUEEN  &  Co.,  from  a  long  and  varied  experience  in  repairing 
all  sorts  and  makes  of  engineering  instruments,  make  it  a  dis- 
tinct aim  so  to  construct  their  transits  that  (i)  they  may  pass 
through  a  certain  amount  of  rough  usage  without  injury,  and 
(2)  may  be  repaired  with  success  even  after  serious  injury. 


QUEEN"  ALT-AZIMUTH. 


A  1480, 


Price,  S55O.OO 


THE  ADJUSTMENTS 

OF  THE 

ENGINEER'S  TRANSIT. 


THE  adjustments  of  an  engineer's  transit  are  of  two 
kinds:  (i)  The  maker's  adjustments,  or  those  which 
reliable  scientific  makers  give  the  instrument  while  it 
is  in  process  of  construction ;  and  (2)  The  field  adjustments, 
or  those  which  occasionally  have  to  be  verified  in  the  accurate 
field  use  of  the  instrument.  The  latter  are,  as  a  matter  of 
course,  included  in  the  former,  since  scientific  makers  always 
find  it  necessary  to  verify  all  the  adjustments,  and  deem  it  an 
essential  requisite  of  a  properly  constructed  and  thoroughly 
tested  instrument,  to  send  it  from  their  hands  only  when  in 
every  respect  accurately  adjusted  for  immediate  use. 

THE  MAKER'S  ADJUSTMENTS. 

In  order  that  the  mathematical  conditions  of  the  practical 
problem  of  angular  measurements  in  the  field  (see  "  Mathe- 
matical Theory  of  t/t:  Errors  of  the  Engineer s  Transit"  this 
Manual)  may  be  realized  in  the  instrument  itself,  itvis  necessary 
that  the  following  points  of  construction  and  adjustment  be 
accurately  attained. 

1.  The  lenses  of  the  objective  and  of  the  eye-piece  of  the 
telescope  truly  centered  in  their  respective  cells. 

2.  The  optical  axis  of  the  system  of  lenses  coinciding  with 
the  mechanical  axis  of  the  tube,  in  all  the  relative  positions  of 
the  objective  and  eye- piece,  the  lenses  remaining  always  at 
right  angles  to  this  axis. 

3.  The  cross  hairs,  during  each  observation,  in  the  common 
focus  of  the  object-glass  and  eye-piece. 

4.  The  vertical  cross  hair  (all  other  adjustments  made)  at 
right  angles  to  the  horizontal  axis  of  the  instrument. 

25 


26  THE    ADJUSTMENTS    OF   THE 

5.  The  line  of  sight  at  right  angles  to  the  horizontal  axis,  or 
coinciding  with  the  axis  of  collimation. 

6.  The  axis  of  the  telescope  level  lying  in  the  'same  plane 
as  the  line  of  collimation,  or  not  "  crossed  "  with  respect  to 
the  collimation  plane. 

7.  The  axis  of  the  telescope  level  parallel  with  the  line  of 
sight. 

8.  The  horizontal  axis  of  the  instrument  at  right  angles  to 
the  axis  of  the  alidade  or  to  the  axis  of  the  upper  plate ;  and 
hence  (all  other  adjustments  made)  the  line  of  sight  always 
lying  in  the  plane   which  is   at  right  angles  to,  and  passes 
through  the  centre  .of,  the  horizontal  graduated  circle. 

9.  The  form  of  the  pivots  of  the  horizontal  axis  the  equiva- 
lent of  true  cylinders. 

10.  The  V's  or  bearings  for  these  pivots  of  equal  form. 

1 1.  The  vertical  graduated  circle  at  right  angles  to  the  hori- 
zontal axis  of  the  instrument. 

12.  The   vertical    graduated    circle   and    its  verniers  truly 
centered  with  respect  to  the  horizontal  axis. 

13.  The   alidade,    or    upper,    plate   at    right    angles  to    its 
axis. 

14.  The  axis  of  the  alidade,  or  upper,  plate  coinciding  with 
the  axis  of  the  lower,  or  circle,  plate. 

15.  The  lower,  or  circle  plate  at  right  angles  to  the  common 
axis  of  both  alidade  and  circle  plates. 

1 6.  The    graduations    of  the    horizontal    circle   and   of  its 
verniers,  true  and   concentric   with  the  common  axis  of  the 
alidade  and  circle  plates. 

17.  The  zeros  of  each  set  of  verniers  or  reading  microscopes 
accurately  180°  apart,  as  measured  at  the  respective  centres 
of  the  graduated  circles. 

1 8.  The  axis  of  each  of  the  alidade  levels  at  right  angles  to 
the  vertical  axis  of  the  instrument. 

19.  The  pivot  of  the  compass  needle  coincident  with  the 
vertical  axis. 

20.  The  zeros  of  the  compass  graduations  in  the  same  plane 
as  the  line  of  collimation. 

21.  The  magnetic  needle  perfectly  straight. 


ENGINEER'S  TRANSIT.  „       27 

22.  The  magnetic  axis  of  the  needle  coinciding  with  the 
axis  of  form. 

23.  The  magnetic  needle  adjusted  for  the  magnetic  dip  of 
the  place  of  observation. 

24.  The  axis  of  the  suspended  plumb-bob  coinciding  with 
the  vertical  axis  of  the  instrument. 

While  it  would  be  difficult  and  unnecessarily  tedious  to  set 
down  every  adjustment  attended  to  by  the  skillful  maker,  the 
foregoing  may  be  taken  as  a  list  of  the  more  prominent  ones. 
Other  adjustments  peculiar  to  the  accessories  of  the  transit 
and  to  special  forms  of  the  transit  will  be  referred  to  in  treat- 
ing of  these  elsewhere. 

THE    FIELD  ADJUSTMENTS. 

The  following  practical  methods  for  detecting  and  correcting 
the  errors  of  an  Engineer's  Transit  are  given  for  use  in  the 
field.  A  full  explanation  of  the  nature  of  each  error  is  also 
made  in  order  that  the  detection  and  correction  may  proceed 
intelligently. 

It  is  not  to  be  inferred  that  QUEEN  &  Co.,  as  scientific  makers 
of  Transits,  pursue  their  tests  of  these  field  adjustments 
exactly  as  the  practical  engineer  is  here  advised  to  do. 
Special  appliances  in  the  form  of  collimating  telescopes  and 
other  delicate  optical  and  mechanical  devices,  enable  their 
adjuster  to  test  and  rectify  the  errors  of  a  Transit  by  refined 
methods  and  consequently  to  secure  a  grade  of  accuracy  in 
these  adjustments  which  can  scarcely  be  equaled  in -the  field, 
even  by  the  accurate  observer. 

First  Adjustment: — -To  make  the  axes  of  the  plate  levels  per- 
pendicular to  the  vertical  axis  of  the  instrument. 

DETECTION  OF  ERROR: — Level  the  instrument  carefully  both 
ways,  care  being  taken  to  make  each  bubble-tube  parallel  to 
a  pair  of  plate-screws.  Turn  the  telescope  through  180°  by 
measuring  on  the  vernier  plate.  This  measurement  should  be 
a  direct  angular  measurement  on  the  plate,  and  not  a  mere 
approximation.  If  the  instrument  is  not  in  adjustment  the 


28 


THE   ADJUSTMENTS    OF   THE 


bubbles,  after  this  revolution,  will  no  longer  remain  in  the 
centres  of  the  tubes.  This  displacement  of  the  bubbles  is 
twice  the  true  error  of  the  instrument.  For  if  aaf  (Fig.  21) 


Fig.  21. 

represent  the  trace  of  the  plane  of  the  bubble-tubes,  oof  the 
vertical  axis  of  the  instrument,  the  turning  through  180° 
would  bring  a  to  a"  and  a'  to  a'n ',  the  angles  a"o'o  and  a'"ofo 
being  respectively  equal  to  ao'o  and  a'o'o.  The  line  KL  re- 
presenting the  proper  position  of  the  bubble-tube  plane,  the 
angle  a'o'a"  will  therefore  be  the  double  error,  and  cause 
twice  the  displacement  of  the  bubbles  due  to  the  true 
error. 

CORRECTION  OF  THE  ERROR  : — To  correct,  bring  the  bubbles 
half-way  back  to  the  centres  of  the  tubes  by  raising  or  lower-t 
ing  either  end  of  the  tubes,  screws  being  placed  there  for  that 
purpose.  Then  level  accurately  by  means  of  the  plate- 
screws. 

This  process  should  be  repeated  several  times,  as  without 
extreme  accuracy  in  this  adjustment,  any  attempt  to  perform 
the  other  adjustments  is  valueless. 

Second  Adjustment: — To  make  the  line  of  sight  coincide  with 


ENGINEER'S  TRANSIT.  29 

the  line  of  collii  nation,  or  to  make  the  line  of  sight  perpendicular 
to  the  horizontal  axis  of  the  telescope. 

DETECTION  OF  THE  ERROR: — The  direction  of  the  line  of 
si^ht  is  determined  by  .two  points,  the  optical  centre  of  the 
object-glass,  and  the  intersection  of  the  cross-hairs.  Of  these 
the  latter  is  movable  and  is  the  part  whose  position  is  to  be 
corrected. 

Set  up  the  instrument,  level  carefully,  and  sight,  Fig.  22,  to 
some  well-defined  point,  A.  Reverse  the  telescope  (i.  e.,  turn 


.— C 
•D 


B 

Fig.    22. 

it  over)  and  sight  to  B.  A  and  B  should  be  as  far  distant  as 
possible  from  the  instrument,  since  the  apparent  deviation  and 
consequently  the  accuracy  of  the  subsequent  correction  in- 
creases as  the  distance.  B  H  should  be  taken  equal  to  A  H. 
If  the  line  of  sight  oo'  be  not  perpendicular  to  the  horizontal 
axis  of  the  instrument  EE ',  A  and  B  will  not  be  on  the  same 
straight  line  with  H.  To  determine  whether  this  is  so  or  not 
turn  the  telescope  around  on  its  vertical  axis  and  sight  to  A. 
The  horizontal  axis  of  the  instrument  now  occupies  the  posi- 
tion E" E'" ,  the  angle  OHE'  of  the  old  position  correspond- 
in-  to  OHE"  in  the  new,  and  the  angle  OHE  to  OHE'". 
\«  »w  reverse  the  telescope  (turn  over  on  horizontal  axis)  ;  its  line 
of  sight  will  strike  this  time  as  far  to  the  left  of  the  line  Aoo' 
as  it  did  before  to  the  right,  that  is  at  C.  The  angle  aHO' 
represents  the  doubled  error,  so  also  does  E" HE,  since  these 
angles  are  equal.  But  the  total  angular  movement  from  B  to 
C  represents  the  sum  of  these  angles,  and  is  consequently 
four  times  the  true  error. 

CORRECTION  OF  THE  ERROR: — To  correct,  with  the  telescope 


THE    ADJUSTMENTS    OF    THE 


pointed  at  C,  place  a  stake  at  D,  the  distance  DC  being  made 
equal  to  one-fourth  BC.  Move  the  cross-hair  ring  by  means 
of  the  capstan-headed  screws  placed  on  the  side  of  the  tele- 
scope, until  the  intersection  of  the  hairs  cuts  the  point  D. 
This  operation  is  accomplished  by  screwing  both  screws  at 
the  same  time,  the  one  in  and  the  other  out.  It  should  be 
remembered  that  an  inverting  or  astronomical  telescope  does 
not  invert  the  motion  of  the  cross-hair  ring,  and  hence  the 
screws  must  be  turned  so  as  to  move  the  rino-  in  the  same 

& 

direction  as  that  apparently  required  to  produce  coincidence. 
With  the  usual  terrestrial  or  erecting  telescope  the  screws 
must  be  turned  so  as  to  move  the  ring  in  the  opposite  direction 
from  that  which  the  error  apparently  requires. 

Third  Adjustment: — To  make  the  line  of  collimation  revolve  in 
a  vertical  plane, 

DETECTION  OF  THE  ERROR  : — Set  up  the  instrument,  and 

,  level   carefully.       Sight    to.          p 

\  i  some    high     object.       The 

^         I  top  of  a  steeple  is  generally 

*        /'  most  convenient.     Depress 

the  telescope  and  note  care- 
fully where  the  intersection 
of  the  cross  hairs  cuts  the 
ground.  Turn  the  instru- 
ment through  1 80°  (this 
time  only  approximately) 
and,  reversing  the  telescope, 
sight  to  the  same  high 
point,  depress  the  tube 
again,  and  again  note  where 
the  line  of  collimation 
strikes  the  ground.  The 
fault  to  be  remedied  is  that 
the  horizontal  axis  of  the 

telescope  is  not  parallel  to 
Fig.  23.  the  plane  of  the  plate  bub_ 

bles.     (Fig.  23.)     Turning  through  180°  brings  the 
support  A  to  A'  and  inclines  the  axis  as  represented     Fig.  24. 


ENGINEERS    TRANSIT.  31 

by  the  dotted  line  A' W ,  the  angles  BOA9  or  B'OA  represent- 
ing the  doubled  error,  since  the  line  drawn  through  O  parallel 
to  the  bubble-plane  would  bisect  them  both. 

The  motion  of  the  line  of  collimation  is  represented  in  Fig. 
24.  /'being  the  high  point,  K and  L  the  two  points  on  the 
ground ;  M  being  the  middle  point  which  the  cross  hairs 
should  cut  if  the  instrument  were  in  adjustment. 

CORRECTION  OF  THE  ERROR  : — To  correct,  therefore,  raise  or 
lower  one  end  of  the  axis  AB  by  means  of  a  screw  placed  in 
the  standard  for  that  purpose,  until  the  line  of  sight  revolves 
in  the  plane  from  P  to  M.  The  reflection  in  a  basin  of  mer- 
cury of  the  high  point  will  suffice  to  determine  the  point  J/, 
and  the  consequent  error  KM  or  ML  be  determined  without 
the  reversal  of  the  telescope.  Instead  of  a  very  high  terrestrial 
object  a  star  may  be  advantageously  used  in  this  reflection- 
method. 

Fourth  Adjustment: — To  make  the  axis  of  the  telescope  level 
parallel  to  the  line  of  collimatioK. 


Fig.  25. 

DETECTION  OF  THE  ERROR  : — Drive  two  stakes  several  hun- 
dred feet  apart.  Set  up  midway  between  them  and,  using  the 
instrument  as  a  level,  bring  the  long  bubble  to  the  centre  of  its 
tube.  Sight  to  a  rod  held  on  each  stake.  The  difference  of 


32  THE    ADJUSTMENTS    OF    THE 

these  readings  will  be  the  true  difference  of  height  between 
the  points,  no  matter  what  the  error  of  the  instrument  may  be. 
For  if  eOj  Fig.  25,  represent  the  position  of  the  telescope,  the 
line  of  sight  will  cut  the  rod  at  A.  Turning  the  telescope 
around  horizontally  while  the  spirit  level  / 1'  still  indicates  the 
same  horizontal  reading,  the  new  position  of  the  line  of  sight 
will  be  cf o'  and  will  intersect  the  rod  set  over  D  at  C. 
CD — AJ5=truG  difference  of  height  of  points  D  and  B.  For, 
since  EF  represents  the  proper  position  of  the  telescope,  then 
FD — £/?— true  difference  of  height  of  points,  and  since  6*  is 
midway  between  B  and  D,  the  angles  which  eo  and  e' o' ,  the 
two  positions  of  the  telescope,  make  with  EF,  being  equal, 
must  be  subtended  by  equal  distances  on  the  rod,  or  EA=FC, 
hence  adding  to  FDand  EB,  we  have  (7^9 +/^)—  (J5B+EA)= 
true  difference  of  height  of  points  (since  this  addition  does  not 
affect  the  balance  of  the  equation),  or  true  difference— 
CD—AB,  as  we  stated  at  first. 

•Now,  clearly,  having  determined  the  true  difference  of  height 
of  the  points,  the  instrument  must  be  corrected  so  as  to  meas- 
ure this  accurately. 

CORRECTION  OF  THE  ERROR  : — Now  set  up  the  instrument 
over  one  of  the  stakes,  measure  the  height  of  the  cross  hair 
above  the  top  of  the  stake,  either  by  direct  reference  to  the 
horizontal  set  of  screws  of  the  cross-hair  ring,  or  by  looking 
through  the  objective  toward  a  graduated  rod  held  at  a  dis- 
tance of  about  a  quarter  of  an  inch  from  the  eye-end,  and 
with  a  neat  lead-pencil  point  marking  on  the  rod  the  centre 
of  the  small  field  of  view.  Set  the  target  on  the  rod  to  this 
reading  plus  or  minus  the  difference  of  height  between  the 
points,  according  as  the  point  set  up  over  is  higher  or  lower 
than  the  second.  Now  sight  to  the  rod  thus  adjusted  and 
held  on  the  second  stake,  and  note  if  the  cross  hairs  cut  the 
target  in  the  centre,  when  the  long  bubble  is  in  the  centre  of 
its  tube.  If  not,  correct  by  lowering  or  raising  one  end  of 
the  level  tube  by  means  of  nuts  placed  there  for  that  purpose, 
until  the  desired  intersection  is  obtained,  the  bubble  still  re- 
maining in  the  centre  of  the  tube.  Here  the  height  of  the 
cross  hairs  above  the  point  over  which  the  instrument  is  set 


ENGINEERS    TRANSIT. 


33 


up  15  very  approximately  independent  of  any  accuracy  of 
adjustment.  The  entire  error  of  the  instrument  is  therefore 
shown  by  its  deviation  from  the  true  reading  as  indicated  on 
the  rod,  by  the  distance  of  the  cross-hair  intersection  from  the 
centre  of  the  target. 

This  adjustment  will  be  further  discussed  in  the  article  of 
this  Manual  on  "  The  Adjustments  of  the  Engineer's  Level." 

Fifth  Adjustment : — To  make  the  vertical  circle  read  zero  when 
the  bubble  of  the  telescope  level  is  in  the  centre  of  its  tube. 

DETECTION  OF  THE  ERROR  : — This  may  be  done  in  two  ways. 
1st.     By  simple  inspection. 
2d.  By  reversion. 

Bv  REVERSION  : — Sight  to  some  distinct  point,  note  the  read- 
ing on  the  vertical  circle.  Turn  the  instrument  around  hori- 
zontally half-way,  reverse  the  telescope,  and  sight  again  to  the 
same  point.  One-half  the  difference  of  the  readings  is  the 
error,  it  having  been  doubled  by  reversion. 

CORRECTION  OF  THE  ERROR  : — The  correction  is  made  by 
moving  either  the  vernier  or  circle  by  loosening  screws  de- 
signed for  the  purpose  of  permitting  circular  motion.  "  The 
index  error  "  may,  however,  be  simply  noted,  and  each  obser- 
vation corrected  by  the  required  amount.  Inspection  is  the 
readiest  method  by  which  to  perform  the  above  adjustment, 
but  when  the  index  error  is  small  and  difficult  of  detection, 
doubling  it  increases  the  accuracy  of  the  correction. 

This  error  if  it  be  small  and  the  vertical  circle  have  but  one 
vernier,  may  also  be  corrected  by  first  setting  the  circle  so  as 
to  read  zero  altitude  and  bringing  the  bubble  of  the  tele- 
scope level  to  a  zero  reading ;  and  then,  by  the  method  of  the 
fourth  adjustment,  moving  the  cross-hair  ring  up  or  down  so 
as  to  bring  the  line  of  sight  parallel  to  the  axis  of  the  tele- 
scope level. 

Sixth  Adjustment: — To  make  the  vertical  cross  hair  truly  ver- 
tical when  the  instrument  is  leveled. 

DETECTION  OF  THE  ERROR  : — Set    up  the   instrument  and 


34 


THE    ADJUSTMENTS    OF    THE 


Suspend  a  plumb  line  from  some  convenient 


Bring  the  vertical  cross  hair 


Fig.  26. 


level  carefully, 
point. 

into  coincidence  with  it,  and  note 
whether  the  line  and  hair  cor- 
respond throughout  their  entire 
length.  If  they  do  not,  the  hair  is 
•out  of  adjustment,  because,  if  the 
instrument  be  properly  leveled  the 
plumb  line  will  be  perpendicular  to 
the  plane  of  the  bubble  tubes. 

The  same  error  may  be  detected 

by  plunging  the  telescope  and  noting  if  the  vertical  hair  passe's 
over  some  point  sighted  to,  throughout  its  entire  length. 

CORRECTION  OF  THE  ERROR  : — To  correct  the  error  the 
cross-hair  ring  must  be  moved  circularly.  This  is  accom- 
plished by  loosening  the  four  screws  of  the  cross-hair  ring. 
These  screws  penetrate  the  ring  a  short  distance,  as  shown  in 
Fig.  26,  and  are  allowed  a  certain  amount  of  play  sidewise  by 
reason  of  the  enlargement  of  the  space  through  which  the 
screw  is  inserted.  When  the  screw  is  tightened  the  piece  just 
below  the  head  of  the  screw  is  clamped  fast  to  the  telescope 
tube.  When  all  four  screws  are  loosened,  however,  it  permits 
the  ring  to  be  turned  through  a  distance  limited  by  the  edges 
of  the  hole  through  which  the  screw  is  inserted.  The  verti- 
cal hair  alters  its  direction  with  the  turning  of  the  ring. 

Relative  Value  of  the  Adjustments : — For  pure  transit  work, 
by  which  we  mean  the  running  of  straight  lines,  the  measur- 
ing of  horizontal  angles,  and  the  like,  the  first  three  adjust- 
ments are  the  most  important.  The  fourth  and  fifth  refer  to 
the  instrument  when  used  as  an  engineer's  level,  while  the 
sixth,  though  classed  with  the  first  three,  is  by  no  means  esien- 
tial.  Indeed,  this  adjustment  should  be  seldom  made,  inas- 
much as  its  performance  is  liable,  by  moving  the  cross-hair 
intersection  eccentrically,  to  displace  the  second  and  third, 
which  have  already  been  performed.  Should  an  adjustment 
of  the  vertical  hair,  however,  become  necessary,  the  second 
and  third  must  be  tested  again  so  as  to  insure  their  non-dis- 
turbance. The  verticality  of  the  hair,  though  not  absolutely 


ENGINEER'S  TRANSIT.  35 

necessary  for  accurate  work,  is  exceptionally  convenient  for 
determining  the  true  perpendicular,  when  only  a  small  portion 
of  a  rod  sighted  to  can  be  seen.  Frequent  tests  of  the  vertical 
hair  are  useful,  but  its  adjustment  is  unwise  unless  followed 
by  a  readjustment  of  the  instrument  in  regard  to  the  line  of 
collimation. 

General  Remarks  on  the  Adjustments : — It  is  well,  to  note 
that  all  of  these  adjustments,  except  the  fourth,  can  be  per- 
formed while  the  instrument  still  remains  in  one  position. 
The  fourth  being  entirely  independent  of  the  rest  may  be  left 
until  the  last,  and  indeed  is  sometimes  entirely  omitted,  as  the 
use  of  the  transit  as  a  level  is  comparatively  rare. 

The  great  fault  of  young  surveyors  is  to  blame  inaccuracies 
in  their  work  upon  a  faulty  construction  of  the  instrument 
For  this  there  is  no  excuse.  Errors  may  arise  from  three  causes : 

(i)  Errors  in  or  damages  to  the  parts  of  the  instrument; 
(2)  insufficient  adjustment,  and  (3)  carelessness  in  setting  up  or 
in  sighting.  The  last  are  by  far  the  most  probable  causes  of 
inaccuracies  in  work,  and,  if  the  adjustment  be  unsatisfactory, 
the  surveyor  has  no  one  to  blame  but  himself,  while  errors  in 
the  instrument  can  always  be  detected  by  the  refusal  of  the  in- 
strument to  respond  to  repeated  tests  while  being  adjusted. 
In  the  latter  case,  the  only  remedy  beyond  obtaining  a  new 
instrument  is  to  note  carefully  what  species  of  errors  are  likely 
to  occur,  and  so  to  handle  the  instrument  as  to  avoid  them  a~ 
far  as  possible. 

A  wide  and  nearly  level  stretch  of  country  is  by  all  means 
preferable  for  the  performance  of  the  adjustments.  The  sights 
taken,  except  those  in  the  fifth  and  sixth  adjustments,  should 
be  as  long  as  possible,  so  that  the  ensuing  apparent  error  may 
be  greater. 

After  the  surveyor  has  used  his  instrument  for  some  time 
he  may  be  sufficiently  competent  to  judge  of  its  accuracy. 
Until  then  the  instrument  should  be  tested  at  least  once  a 
week,  if  not  more  frequently.  If  he  should  find  the  instru- 
ment one  of  accuracy  and  great  permanency  of  parts,  less 
frequent  adjustments  may  be  made.  Adjustments  should  al- 
ways be  made  if  the  instrument  suffers  a  fall  or  if  the  surveyor 
has  reason  to  believe  that  a  severe  jar  has  happened. 


36  THE   ADJUSTMENTS    OF    THE    ENGINEER'S    TRANSIT. 

The  field  adjustments  of  the  compass  as  attached  to  the  or- 
dinary form  of  the  Engineer's  Transit  are  essentially  the  same 
as  those  of  the  Surveyor's  Compass.  They  will  be  found  fully 
treated  in  the  article  of  this  Manual  on  "  The  Adjustments  of 
the  Engineer's  Compass" 

THE  FOREGOING  METHODS,  we  would  again  remind  engineers, 
while  essential  to  the  proper  testing  and  use  of  a  Transit,  are 
intended  only  as  instruction  in  practical  field  adjustments,  and 
these  do  not  take  the  place  of  the  permanent  adjustments 
given  by  scientific  makers,  although  they  are  to  some  extent  a 
test  of  the  latter. 

THE  ATTENTION  OF  ENGINEERS  is  particularly  called  to  the 
methods  of  elimination  of  error  and  the  methods  of  instru- 
mental manipulation  suggested  by  the  article  of  this  Manual, 
entitled  "  The  Mathematical  Theory  of  the  errors  of  the  Engi- 
neers Transit"  A  summarized  statement  of  the  means  for 
avoiding  and  eliminating  the  various  forms  of  error  is  given 
at  the  close  of  the  same  article. 

QUEEN  &  Co.  pay  great  attention  to  the  theoretical  accuracy 
and  practical  permanency  of  all  the  adjustments  in  order  that 
the  engineer  receiving  a  perfectly  adjusted  and  durable  instru- 
ment may  with  reasonable  use  of  it,  for  years  secure  a  high 
degree  of  accuracy  in  his  work  with  the  minimum  expenditure 
of'time  and  trouble. 

A  SPECIAL  CERTIFICATE,  indicating  all  the  instrumental  con- 
stants and  data  required  to  be  known  by  the  engineer  in  the 
more  scientific  methods  of  manipulation,  is  furnished  by  QUEEN 
&  Co.  with  each  instrument.  This  certificate  recites 

(1)  The  magnifying  power  of  the  telescope. 

(2)  The  angular  value  of  the  field  of  view  of  the  telescope. 

(3)  The  angular  value  of  one  division  of  each  of  the  pfote 
levels. 

(4)  The  angular  value  of  one  division  of  the  telescope  level. 

(5)  The  "  least  count "  of  each  of  the  verniers,  or  the  con- 
stants of  each  of  the  reading  microscopes. 

(6)  The   constants  peculiar  to   the   accessory  parts   of  the 
Transit,  as,  for  example,  the  stadia  hairs,  the  gradienter  screw, 
the  filar  micrometer,  and  the  solar  attachment. 


QUEEN"  CITY  AND  BRIDGE  TRANSIT. 


A  1490.  Price,  $25O. 

The  most  accurate  and  best  finished  High  Grade  Transit  made. 


THE  MATHEMATICAL    THEORY 

OF    THE 

ERRORS  OF  THE  ENGINEER'S  TRANSIT, 


ALTHOUGH  the  practical  treatment  of  the  field  adjust- 
ments has  required  some  explanation  of  the  nature  of 
the  errors  to  which  the  transit  is  liable,  it  is  important  that  this 
matter  be  presented  in  a  more  mathematical  and  complete  form. 
Alike  the  scientific  construction  and  the  intelligent  use  of  a 
theodolite  require  as  basis  of  such  construction  and.  use  a 
thorough  discussion  of  the  errors.  For  the  maker,  such  a  dis- 
cussion determines  the  elements  to  which  special  attention 
must  be  given  in  order  to  attain  the  highest  constructive  re- 
sult. For  the  user  it  suggests  the  methods  of  manipulation 
and  schemes  of  observation  necessary  in  order  to  eliminate  the 
small  outstanding  errors  of  adjustment. 

It  is  found  convenient  to  treat  the  subject  under  two  general 
heads : 

I.  Tlie  Axial  Errors,  or  errors  due  to  the  incorrect  direction 
of  the  three  principal  axes  of  the  instrument.  II.  The  Errors 
of  Eccentricity  and  of  Graduation,  or  those  pertaining  to  the 
reading  of  angles  by  means  of  the  graduated  circle. 

I.    THE   AXIAL   ERRORS. 

In  discussing  the  axial  errors  of  an  altitude-azimuth  instru- 
ment we  limit  ourselves  to  a  form  of  treatment  best  suited  to 
an  estimate  of  the  effect  of  the  given  errors  on  the  angular 
measurements.  For  the  methods  of  determining  by  means  of 
refined  observation,  the  amount  of  the  errors  of  an  altazimuth 
we  refer  the  reader  to  Chauvenet's  Spherical  and  Practical  As- 
tronomy, Vol.  II,  Chapter  VII;  to  Briinnow's  Traitt  a" astron- 
omic sphsriqiic  et  d' astronomic  pratique ',  Edition  Franqaise,  par 
C.  Andre,  Vol.  II,  Chapter  III,  or  other  standard  works  on 
practical  astronomy  and  geodesy.  The  following  discussion 
is  largely  due  to  Dr.  \V.  Jordan's  Handbuch  der  Vermessungs- 

37 


38  THEORY    OK    THE    ERRORS 

kunde,  dritte  verbesserte  und  envsiterte  Auflage,  and  to  this 
work  as  well  as  to  Bauernfeind's  Vermessungskitnde  we  refer 
the  reader  for  a  treatment  in  some  particulars  more  extended 
and  detailed. 

There  are  three  principal  axes  of  the  transit,  and  there  is 
also  one  accessory  axis,  namely,  the  level  axis.  Let  us  desig- 
nate : 

I.  The  Sight  axis,  5. 
II.  The  Horizontal  axis,  H. 

III.  The  Vertical  axis,  F,  and 

IV.  The  Level  axis,  L. 

The  following  theoretical  conditions  are  then  to  be  fulfilled 
in  the  perfectly  adjusted  and  accurately  set-up  instrument: 

(1)  5 -L //,   or  sight  axis   of  telescope  at  right    angles  to 
horizontal  axis  of  telescope. 

(2)  //_L  V,  or  horizontal  axis  of  telescope  at  right  angles  to 
vertical  axis  of  instrument. 

(3)  L  _L  F,  or  level  axis  of  (each)  plate  level,  or  of  the  strid- 
ing level,  at  right  angles  to  vertical  axis  of  instrument. 

The  construction,  final  adjustment,  and  setting-up  of  the 
instrument  should  permit  these  conditions  to  be  accurately 
attained.  Yet,  since  all  adjustments  depending  upon  delicacy 
of  manipulation  are  in  the  last  analysis  only  approximations, 
it  is  highly  important  to  know  what  the  effect  of  any  small 
outstanding  errors  of  (i),  (2),  and  (3)  will  be  on  the  angular 
measurements  made.  The  question  plainly  put  is  :  Admitting 
a  given  error,  what  will  be  its  effect  on  any  proposed  angular 
measurement ;  and  which  of  the  three  given  conditions,  SJL  H, 
//J_  V,  L  J_  V,  for  a  given  error,  produces  the  most  serious 
effect  on  the  angular  measures  ?  Since  there  are  two  kinds  (if 
angles  measured  by  the  transit,  namely,  horizontal  and  vertical, 
or  angles  of  azimuth  and  angles  of  altitude,  it  becomes  necessary 
to  consider  the  effect  of  these  errors,  with  respect  to  these 
classes  of  angles,  separately.  Investigation  having,  however, 
shown  that  the  axial  errors,  though  bearing  important  relations 
to  the  measurement  of  horizontal  angles,  have  but  a  slight  in- 
fluence on  vertical  angles,  the  major  discussion  will  naturally 
concern  the  former. 


OF     THE     ENGINEER  S    TRANSIT. 


39 


I.  EFFECT    OF  THE    AXIAL    ERRORS    ON   THE 
MEASUREMENT  OF  ANGLES  OF   AZIMUTH. 

(A.)  ERROR  IN  THE  CONDITION  S  _L  H. 

If  the  line  of  sight  is  not  at  right  angles  to  the  horizontal 
axis  but  makes  any  angle,  say  90°  —  c,  the  quantity,  c,  is  the 
error  of  the  line  of  sight  or  the  collimation  error.  The  effect 
of  such  an  error,  r,  on  measurement  of  horizontal  angles  is 
best  seen  from  Fig.  27. 

In  this  figure  MN  is  the 
horizontal  axis,  OZ  is  the 
vertical  axis,  while  OZ'  , 
OP,  and  OS'  are  three  po- 
sitions of  the  inaccurately 
adjusted  sight  axis  or  line 
of  sight,  which  makes  re- 
spectively the  equal  angles  Fig.  27. 

Z'OZ,  FOR,  S'OT,  or  f, 

with  the  plane  ZRT,  so  that  Z'PS'  is  a  parallel  to  the  great 
circle  ZRT. 

Let  the  sight  axis  be  directed  to  a  point  P  whose  altitude  is 
PS=h.  Then,  if  the  sight  axis  were  accurately  collimated, 
P  would  be  projected  on  the  horizon  at  S.  But  with  the  error 
r  in  collimation  it  is  projected  at  S'.  PR,  as  the  arc  of  a 
parallel  to  MTV,  very  approximately  equals  c.  For  any  alti- 
tude //,  the  error  r,  or  PR,  projected  on  the  horizon,  is  S.T,  or 
SS'  in  excess  of  the  effect  of  the  same  error  on  a  hori- 
zontal pointing.  For  varying  altitudes,  therefore,  the  given 
error  consists  of  a  constant  part  S'T  and  a  variable  part  SSr. 
Denoting  ST  by  Z,  S'T  by  c,  and  55'  by  (c),  we  evidently 
have  from  the  figure 


and  because  PR  may  be  assumed  as  approximately  equal  to  c 
and  is  the  arc  of  a  parallel  to  ST. 

Z=e  sec.  //  (i) 

and  inserting  this  value  in  the  previous  equation,  we  have 

(c)  =c  sec.  h  —  c  (2) 

which  allows  the  variable  collimation  error  to  be  computed  as 


40  THEORY    OF    THE    ERRORS 

a  simple  function  of  the  assumed  constant  error  c  and  the 
altitude  h. 

The  following  table,  for  various  assumed  altitudes  and  va- 
rious assumed  values  of  <r,  will  give  a  practical  idea  of  the 
effect  of  collimation  error  upon  measurements  of  horizontal 
angles  with  the  line  of  sight  directed  to  the  given  altitude. 

TABLE  SHOWING  EFFECT  OF  AN  ERROR  c  OF  COLLIMATION 
ON  MEASUREMENT  OF  HORIZONTAL  ANGLES. 


ALTITUDE  h. 


c 

i° 

2° 

3° 

4° 

5° 

10° 

20° 

45° 

60° 

10" 

o.oox/ 

O.OI/X 

O.OI" 

O.O2X/ 

o.o4x/ 

0.15" 

0.6" 

o'    4" 

I0// 

1/           O.OI 

0.04 

0.08 

0.15 

0.23 

0-93 

39 

o    25 

I' 

2' 

O.O2 

0.07 

0.16 

0.29 

0.46 

1.85 

7-7 

o    50 

2' 

S/ 

10' 

0.05 
O.O9 

0.18 

0-37 

0.41 
0.82 

0-73 
1.46 

I.I5 
2.29 

4-63 
9.26 

19.3 

385 

2     04 

4    09 

5' 

10' 

15'     i  0.14 

o-55 

1.24 

2.  2O 

3-44 

13.88 

57.8 

6    13 

15' 

THE  PRACTICAL  DEDUCTIONS  from  the  preceding  discussion 
are: 

First.  The  constant  part,  S'T,  of  the  projected  collimation 
error  is  eliminated  by  taking  the  difference  of  the  two  readings 
for  any  two  pointings,  and  hence  is  not  ordinarily  in  question, 
in  measurement  of  horizontal  angles. 

Secondly.  The  varying  part,  SS',  of  the  projected  collima- 
tion error,  or  the  collimation  error,  is  also  eliminated  by  tak- 
ing the  difference  of  any  two  pointings  of  the  same  altitude. 

For,  representing  the  collimation  error  due  to  two  pointings 
of  different  altitude,  /^  and  h.2,  by  dc,  or,  what  comes  to  ths 
same,  letting  J  c  =  (c\ — (V)2,  we  have  evidently  from  equa- 
tion (2)  ^ 

Ac  =  c  (sec.  /jj —  sec.  7/2), 

which,  for  7/T  =  h.2>  becomes  zero. 

Thirdly.  The  varying  part,  SS',  of  the  projected  collimation 
error  is  also  for  pointings  of  different  altitudes  eliminated, 
when  the  angle  between  the  two  points  is  determined  by  the 
principle  of  reversion,  or  when  the  angle  is  first  measured  in 
one  position  of  telescope  and  then  the  telescope  turned  over 


OF   THE    ENGINEERS    TRANSIT.  41 

on  its  horizontal  axis  and  round  a  vertical  axis,  the  measure- 
ment again  made,  and  the  mean  of  the  two  measures  taken. 

For,  if  Jc  is  considered  positive  in  one  position  of  the 
telescope  it  must  be  considered  negative  in  the  reverse  posi- 
tion, and  hence,  entering  with  different  signs,  it  is  eliminated 
by  taking  the  mean  of  the  measures  for  the  two  positions  of 
the  telescope. 

Fourthly.  From  the  table  it  is  evident  that  the  collimation 
error  likely  to  exist,  is,  for  low  altitudes,  negligible  even  in 
high-class  work.  Even  for  <:— 10'  and  /i=io°  the  table  shows 
the  error  less  than  10".  The  table  also  shows  the  necessity 
for  painstaking  collimation  or  for  proper  methods  of  elimina- 
tion of  the  error,  when  the  pointings  of  the  telescope  are  of 
any  considerable  altitude. 

(B.)  ERROR  IN  THE  CONDITION  H _L  V. 

If  the  horizontal  axis  of  the  telescope  is  not  at  right  angles 
to  the  vertical  axis  of  the  instrument,  but  makes  an  angle 
90° —  /,  /  is  the  error  of  the  horizontal  axis. 

In  Fig.  (28),  OZ  repre- 
sents the  vertical  axis,  MN 
the  horizontal  axis  at  right 
angles  to  OZ,  or  in  correct 
position,  and  M' N'  the  hori- 
zontal axis  making  an  angle 
/  with  the  correct  position. 
The  line  of  sight  will  there- 
fore move  in  the  plane 
Z'PT  instead  of  the  plane  ZRT,  and  if  directed  to  P,  the  de- 
viation PR  projected  on  the  horizon  will  be  ST.  Let  ZZ'=  i, 
ST=  (/),  TR  =  //,  and  RZ=go°—  h,  then  from  the  figure  we 
have 

PR  ==  (/)  cos.  // ; 
also     PR  =  i  cos.  (90°—  h\ 


or,  PR  =  i  sin. 


42  THEORY    OF    THE    ERRORS 

and  hence,      (2)  cos.  //  =  /  sin.  /i, 

or  finally,       (/)  =  /  tan.  //,  (3) 

from  which  formula  the  following  table  may  be  computed  : 

TABLE  SHOWING    EFFECT  OF   AN  ERROR  i.  OF    HORIZONTAL 
Axis  ON  MEASUREMENT  OF  HORIZONTAL  ANGLES. 


ALTITUDE  h. 

2 

1°               2° 

3° 

4° 

5° 

10° 

20° 

45° 

60° 

10"    0.17"    o.35/x 

0.52" 

0.70"!     0.87" 

1.8" 

3.6" 

C/IO" 

Q'I7" 

i' 

I.O5      i    2.IO 

3-J4 

4.20 

5-25 

10.6 

21.8 

I   OO 

i  44 

2' 

2.09     i    4.19 

6.29 

8.39 

10.50 

21.2 

43-7 

2  OO 

328 

V 

5.24       10.48 

15.72    i  20.98 

26.25 

52.9 

i'49" 

500 

8  40 

10' 

10.47     !  20.95 

31-44 

41  96 

52.49 

I  '46" 

3  3» 

IO  OO 

17  19 

'5' 

15.71      '31-43 

47-17 

i'  3" 

i'i9" 

239 

528 

15  oo 

25  59 

THE  PRACTICAL  DEDUCTIONS  from  this  discussion  are : 
First.  The  effect  of  the  existence  of  an  instrumental  error 
/,  or  of  the  violation  of  the  condition  HA.  V,  may  be  elimi- 
nated by  the  method  of  reversion  observation,  already  ex- 
plained in  the  practical  deductions  concerning  the  collimation 
error,  c. 

Secondly.  The  effect  of  the  error  i  is  also  eliminated  by 
taking  the  difference  of  the  readings  for  any  two  pointings  of 
the  same  altitude.  For,  if  we  represent  the  effective  errors 
for  the  two  altitudes  /^  and  h2  of  an  error  i,  by  (i)^  and  (z')2,  and 
Ji  —  (i )j —  (i )2,  we  have  evidently  from  equation  (3), 

Ji-=  i  (tang.  /^ —  tang.  //2), 

which  for  /^=  h2  becomes  zero. 

Thirdly.  This  error,  /,  is  of  much  more  serious  influence  on 
horizontal  angles  than  the  collimation  error. 

Fourthly.  In   a  thoroughly  tested   and   carefully  adjusted, 
instrument,  and  with  altitudes  less  than  5°,  this  error  need  not 
be  feared,  but  with  an   instrument   having   any  considerable 
error  2,  or  with  pointings  of  a  considerable  altitude,  the  result- 
ing error  (i)  on  the  horizontal  angle  is  serious. 

Fifthly.  It  is  to  be  borne  in  mind  that  in  observations  like 
those,  for  example,  required  in  making  the  third  adjustment, 
the  effective  error,  (f ,  varies  as  the  tangent  of  the  angle  of 
depression  as  well  as  of  elevation. 


OF    THE     ENGINEERS     TRANSIT. 


43 


Fig.  29. 


(C.)  ERROR  OF  DEVIATION  or  THE  VERTICAL  Axis  OF  THE 

IN- I  'KfMENT    FROM  THE  VERTICAL. 

This  is  due  either  (i)  to  error  in  the  condition  L  J_  / ' 
that  is,  inaccurate  adjustment  of  the  level  axis  with  respect  to 
vertical  axis,  or  (2)  to  untruthfulness  and  lack  of  sensitive- 
ness of  the  levels,  or  (3)  to  inaccuracy  of  use  of  the  levels  in 
setting  up  the  instrument. 

In  Fig.  29,  OZ  is  the  ver- 
tical, OZ'  the  vertical  axis 
deviating  from  OZ  by  an 
angle  ZOZ1 ',  which  we  de- 
signate i'.  If  the  axis  <>f 
sight  is  directed  to  P,  this 
point  will  be  projected  to  T 
instead  of  to  ^  ;  and  if  we 
designate  AS  by  ;/  and  A'T 
by  //',  their  difference  will 
be  equal  to  the  desired  projection  error,  which  we  designate 
(?'),  that  is,  ;/  —  //'=  (V).  The  plane  of  the  circle  at  right  angles 
to  the  vertical  axis  will  therefore  take  the  position  A  M  B'  X' 
instead  of  AMBN,  so  that  the  angle  BOB'  between  the 
planes  is  equal  to  v.  The  line  of  sight  being  directed  to  P% 
the  horizontal  axis  must  take  the  position  of  J/Ar/,  at  right 
angles  to  OT  and  approximately  to  OS,  whence  the  inclina- 
tion to  the  true  horizontal  plane  is  JAJJ/",  which  we  designate 
/'.  \Ye  have  now  a  triangle  LJDf  right  angled  at  J/,  whose 
side  LM=  AS  because  AL  and  SM  each  equal  90°.  But 
the  arc  AS  is  the  azimuth  of  the  projected  point  P  as  meas- 
ured from  the  point  of  greatest  inclination  A,  and  this  arc, 
or  its  equal  LM,  we  designate  //.  In  the  right  spherical 
triangle  LMM' ,  LM=  u,  L  =  v,  and  MM'  =  /',  and  hence 

/'=  i'  sin.  u. 

But  an  inclination  i'  of  the  horizontal  a-xis  produced  a  pro- 
jected error  (/')  in  measurement  of  horizontal  angles  in  which, 
according  to  the  previous  article,  (B), 


(/')  =  /'  tang, 


44  THEORY    OF    THE    ERRORS 

and  therefore  (/')  =  v  sin.  u  tang.  //, 

or     (v)  =  v  sin.  u  tang.  //,  (4) 

where  (v)  represents  the  effect  of  v,  for  any  pointing,  as  pro- 
jected on  the  horizon.  For  the  maximum  value  of  sin.  ti,  or 
i,  the  formula  takes  the  form 

(v)  =  v  tang.  //, 

and  the  table  of  the  preceding  section  (B)  gives  the  values  of 
the  effective  error. 

THE  PRACTICAL  DEDUCTIONS  from  consideration  of  this  error 
are : 

First.  The  error  v  made  in  adjusting  and  setting  up  the  in- 
strument cannot  be  eliminated  by  reversion  observations. 

Secondly.  If  we  suppose  an  angle  measured  between  two 
points  of  the  same  altitude  we  can  find  the  expression  for  the 
maximum  value  of  the  error  Av.  Let  //T  and  uv  be  respectively 
the  altitude  and  azimuth  (as  measured  from  point  of  greatest 
inclination  of  horizontal  circle)  of  the  first  point,  and  //2,  7/2,  the 
same  of  second  point,  and  the  difference  between  the  effective 
errors  (v^  and  (z/2)  be  Av,  that  is,  Av=(v^) —  (?/2) ;  then  from 
equation  (4)  we  evidently  have 

Av  =  v  (tang.  /^  sin.  u^  —  tang.  /i.2  sin.  ?/2).  (5) 

This  value  attains,  for  h±  =  //2,  its  maximum  in  relation  to 
«!  and  uz  when  sin.  u^=  —  sin.  ?/2,  or  when  u\  —  ?/2  =  it  180°. 
That  is,  the  error  becomes  greatest  for  hv  =  //2  when  the  angle 
measured  nx — »2  is  180°.  Under  these  conditions  the  above 
formula  (5)  becomes 

Maximum  Av  =  2  v  tang.  //, 

or  the  greatest  error  Av  arising  from  the  error  v  in  vertically 
of  axis  will,  for  a  straight  angle  between  two  points  of  the  same 
altitude,  be  just  double  the  values  set  down  in  the  table  as 
given  in  section  (B). 

Thirdly.  It  is  evident  that  for  altitudes  less  than  5°  and 
with  good  levels  properly  adjusted  and  care  in  setting  up,  no 
appreciable  error  need  be  feared,  even  in  high-class  work. 


OF     THE     ENGINEERS     TRANSIT.  45 

A  FFW  GENERAL  INFERENCES  to  be  drawn  from  the  foregoing 
discussion  of  the  axial  errors  c,  i,  and  v,  may  be  of  practical  use. 

First.  If  we  measure  horizontal  angles  with  an  Engineer's 
Transit  whose  collimation  error  is  c,  error  of  horizontal  axis 
/,  and  whose  vertical  axis  has  a  deviation  of  v  from  the  ver- 
tical, the  three  effective  errors  (c),  (z),  (v),  may  combine  in  a 
total  (s),  so  that  for  a  single  pointing 


and  if  Js   represent  the  total  error   made   in   measuring  an 
angle,  or  for  t\vo  pointings, 

Js  =  Jc+Jc+Jv, 
or  reproducing  their  values  from  sections  (A),  (B),  and  (C), 

Js  =  c  (sec.  //!  —  sec.  //2)  +  i  (tang.  /i{  —  tang.  /i2) 
-f-i'  (tang.  //!  sin.  u^  —  tang.  /i2  sin.  ?/2).  (6) 

Secondly.  From  this  equation  (6)  it  becomes  evident  that  it 
is  of  importance  to  choose  points  nearly  of  the  same  altitude 
if  we  would  by  reversion  eliminate  all  instrumental  errors 
eliminable. 

Thirdly.  Only  th?  collimation  error  c  and  the  error  of  the 
horizontal  axis  i  can  be  eliminated  by  reversion. 

Fourthly.  Since  the  error  of  verticality  of  axis  v  can  be- 
come larger  than  any  other  of  the  errors  and  can  also  have  a 
more  serious  result  on  the  measurement  of  horizontal  angles, 
it  requires  special  attention.  The  error  v,  as  already  stated, 
depends  not  only  on  care  in  the  use  of  the  levels  in  setting  up, 
but  on  their  proper  adjustment,  and  on  their  truthfulness  and 
sensitiveness  as  well.  And  hence  the  careful  attention  (see  the 
article  on  "  The  Spirit  Levels  of  Engineering  Instruments"}  be- 
stowed by  QUEEN  &  Co.  on  the  plate  levels,  as  well  as  on  the 
telescope  and  striding  levels,  of  the  Engineer's  Transit  is  fully 
justified. 


46  THEORY    OF    THE    ERRORS 

THE  EFFECT  OF  THE  AXIAL  ERRORS  ON  THE 
MEASUREMENT  OF  ANGLES  OF  ALTITUDE. 

Having  devoted  considerable  space  to  the  consideration  of 
the  effect  of  small  errors  of  direction  of  the.  three  principal  axes 
apon  the  measurement  of  horizontal  angles,  we  have  now 
briefly  to  speak  of  their  effect  on  measurement  of  angles 
of  altitude.  This  subject  has  been  rather  carefully  in- 
vestigated by  Dr.  W.  Jordan  in  his  inimitable  Handbuch  dcr 
Vermessungskunde,  Vol.  II,  and  we  give  here  as  a  matter  of 
considerable  interest  the  general  result  of  a  cumbrous  mathe- 
matical discussion. 

For  a  fairly  adjusted  altazimuth  instrument  and  for  vertical 
angles  not  exceeding  45°,  the  effect  of  the  usual  small  errors 
is  altogether  inappreciable.  For  angles  of  greater  altitude 
than  45°  and  when  extreme  accuracy  is  required,  greater  care 
than  usual  must  be  taken  with  the  adjustments.  It  is  to  be 
noted,  however,  that  now  we  speak  only  of  extreme  accuracy 
and  of  instruments  reading  vertical  angles  to  seconds  of  arc. 
For  a  total  error  of  the  axes  of  10'  the  sum  total  of  effective 
error  on  a  vertical  angle  of  45°  is  only  0.87",  of  60°  only 
1.51",  and  for  a  total  error  of  30'  for  vertical  angle  of  40°  it  is 
only  7.86",  and  for  60°  only  13.60". 

Therefore,  even  in  the  use  of  a  fine  geodetic  instrument,  the 
three  axial  errors  do  not,  with  reasonable  precautions,  produce 
any  error  in  measuring  angles  of  altitude  less  than  60°.  Of 
course,  in  the  use  of  the  Engineer's  Transit,  these  axial  errors 
produce  an  entirely  inappreciable  effect  on  measures  of  mode- 
rate angles  of  altitude  and  are  not  in  question. 

It  would,  however,  be  an  entire  misconception  to  suppose 
that,  since  the  axial  errors  do  not  have  an  appreciable  influence 
in  the  measurement  of  vertical  angles,  no  errors  are  therefore 
to  be  feared  in  such  measurement.  The  constant  errors,  such  as 
the  errors  of  graduation  and  of  eccentricity  of  the  circle,  and 
particularly  the  index  error  and  the  error  of  the  level  lying  in 
the  same  plane  as  the  circle,  are  the  ones  requiring  closest 
attention.  Their  elimination  can  be  accomplished  only  by 
special  methods  of  work  and  proper  instrumental  adjustment 
and  design. 


QUEEN"  FULL  ENGINEERS'  TRANSIT. 


A  1494, 


Price,  $185.00 


QUEEN"  FULL  SURVEYORS'  TRANSIT. 


A  1502. 


Price,  $140.00 


OF     THK     ENGINEERS     TRANSIT.  47 

II.  THE  ERRORS  OF    ECCENTRICITY  AND  OF 
GRADUATION. 

Having  treated  the  axial  errors,  we  still  have  to  consider 
those  errors  which  are  due  to  (i),  the  eccentricity  of  the  tele- 
scope; (2),  the  eccentricity  of  the  circle;  (3),  the  eccentricity 
of  the  verniers,  and  (4)  the  inaccuracies  of  graduation. 

THE  ECCENTRICITY  OF  THE  TELESCOPE. 
Assuming,  in  the  first  place,  that  there  is  no  eccentricity  of 
the  circle  or  of  the  vernier,  there  may  still  be  an  eccentricity 
of  the  telescope,  on  account  of  the  line  of  sight  not  being 
mounted  directly  over  the  centre.  In  Fig.  29  the  eccentricity 
of  the  line  of  sight  of  the  telescope  is  represented  by  the  ra- 

P, 

f. 


Fig.  29. 

dius  of  a  circle  conceived  as  described  about  the  centre,  C,  of 
the  circle.  All  lines  of  sighting  will  be  tangent  to  this  circle. 
Pl  and  P2  are  two  points  to  which  the  eccentrically  placed 
telescope  is  in  turn  directed,  and  between  which  it  is  intended 
to  measure  the  angle.  The  angle  «  represents  the  true  angle, 
while  a!  and  a!'  represent  the  angles  measured  with  two  posi- 
tions of  the  eccentric  telescope.  A  simple  inspection  of  the 
figure  gives  us  the  following  relations  : 

a  -\-  v  =  x  =  «'  +  n  a-\-u  —  y  =  a"  4-  v 

1<  (l)  a  —  «"  =  i*  —  u  (2) 


«"-«'  =  2(H  —  r)         (3)  «=       2'  (4) 

If  the  respective  distances  of  Pl  and  P2,  from  the  centre,  are 
{  and  d2,  and  the  eccentricity  or  radius  of  the  small  circle  of 


48  THEORY     OF     THE     ERRORS 

the  figure  is  represented  by  ey  the  angles  of  11  and  v  may  be 
expressed  in  seconds  as  follows : 

u  =  206265  4r-  v  =  206265  -4-  (S) 

</,  d2 

Inserting  these  values  in  equation  (i)  we  have: 

« 

a  — •  a'  =  206265  *  (-4 ^-).  (6) 

</,         df, 

Inspecting  this  equation  we  see  that  when  dl  and  d^  are 
equal  to  each  other,  a  —  a'  —  o,  or  there  is  in  this  case  no  cor- 
rection to  be  applied  for  eccentricity  of  telescope.  We  also 
note  that  a  —  a'  increases  with  e  and  with  the  difference  be- 
twef  i  dv  and  d.2. 

/f  ssuming  numerical  values  for  e,  d^,  and  d2,  we  may  compute 
the  value  of  o.  —  a'.  Let,  for  example,  e  =  0.005  inch,  dl  =  20 
ft,  and  d2=  120  ft;  then  inserting  these  values  in  (6)  we  find 
a  —  a'  =  3.5".  It  is  thus  seen  that  when  an  important 
angle  is  to  be  measured  the  error  of  eccentricity  of  the  tele- 
scope may  become  sensible,  and  the  observations  should  be 
conducted  so  as  to  eliminate  the  error. 

It  is,  however,  also  seen  from  equation  (4)  that  a  mean  of 
two  observations  with  telescope  in  different  positions,  direct  and 
transited,  gives  the  angle  free  from  this  error. 

Therefore,  to  eliminate  error  of  eccentricity  of  telescope, 
read  the  angle  in  one  position  of  the  telescope ;  then  transit 
the  telescope  and  read  the  angle  again  and  take  the  mean  of 
the  two  readings.  This  rule  applies  to  all  engineers'  transits, 
no  matter  how  distant  from  the  centre  of  circle  the  telescope 
may  be,  and  hence  also  suggests  how  the  eccentrically  placed 
telescopes  of  mining  transits  maybe  used  for  accurately  meas \ 
uring  horizontal  angles. 

THE  ERRORS  OF  ECCENTRICITY  OF  THE 
CIRCLE. 

THE  ERRORS    PERTAINING    TO  THE    GRADUATED    CIRCLE  are  of 

four  kinds  :  (i.)  The  error  arising  from  the  non-coincidence  of 
the  centre  of  the  graduated  circle  with  the  centre  of  rotation, 


OF     THE     ENGINEER  S     TRANSIT. 


49 


or  the  error  of  eccentricity  of  the  circle.  (2)  The  error  aris- 
ing from  the  non-intersection  of  the  centre  of  rotation  by  the 
straight  line  joining  the  zeros  of  the  verniers  or  microscopes, 
or  the  error  of  eccentricity  of  the  verniers  or  microscopes,  due 
to  their  zeros  not  being  exactly  180°  apart,  as  measured  at  the 
centre  of  the  circle.  (3)  Errors  due  to  faulty  graduation ; 
and  (4)  Errors  due  to  inaccurate  estimate  in  reading  the  ver- 
niers or  microscopes. 

THE  ERROR  OF  ECCENTRICITY  OF  THE  CIRCLE  may  be  investi- 
gated as  follows :  In  the  accompanying   Fig.  30   let  C  be  the 


J80° 


centre  of  the  alidade,  C  that  of  the  circle,  CO  the  eccentricity, 
e,  and  A' A"  or  2AA'  the  effective  error,  e,  of  the  eccentricity. 
Let  AB  be  a  straight  line  joining  the  zeros  of  the  verniers  or 
microscopes  ;  A  the  reading  of  vernier  A,  B  of  B,  A'  the  true 
reading  of  vernier  A,  B'  the  true  reading  of  vernier  B.  Then 
assuming  that  by  careful  centering  of  the  instrument  e  has 
been  made  very  small,  the  arc  A  A'  may  be  regarded  as  equal 
to  the  perpendicular  CD  ;  and,  therefore,  representing  the  arc 


50  THEORY     OF     THE     ERRORS 

£O°  by  E  and  O°Af,  as  already  stated,  by  A',  or  the  angle 
EC' A'  by  (E-\-Af\  and  representing  the  radius  C'Ar  by  r 
and  206265"  by  s  we  have,  from  the  triangle  COD,  the  follow- 
ing expression, 

AA' '  =  —  sin. 

But  since  sin.  (E-\-Af)  and  sin.  (E-\-A)  are  sensibly  the 
same  we  may  write 

AA'  =  —  sin.  (E-\-A)  (i) 

*  r 

If  we.  now  allow  B  to  coincide  with  B' ',  the  vernier  line  of 
the  alidade  will  lie  in  the  direction  B'A",  and  the  effective 
error  clue  to  the  eccentricity  of  the  circle  will  be  the  arc 
A" A'  =  2  AA'  =  the  central  angle  e.  We  have,  therefore, 
finally  the  following  expression  for  the  error  due  to  eccen- 
tricity of  the  circle  : 

e  =    l±L    sin.  (E+A).  (2) 

This  equation  shows  that  for  the  direction  EF,  when 
sin.  (E-\-A)  =  o,  the  error  e  becomes  zero,  and  that  for 

(E-\-A)  =  =b  90°,  e=  ± ,  which  is  the  maximum  value 

r 

for  the  error  due  to  the  eccentricity  of  the  circle. 

It  is  also  evident  that  from  (E+A)  =  o°  to  (E+A)  = 
-j-i8o°  a  positive  series  of  e  results,  and  from  o°  to  — 180°  a 
negative  series  of  e.  Hence,  if  but  one  vernier  is  read  in  a 
given  position  of  the  telescope,  the  telescope  then  transited 
and  directed  to  the  same  object,  and  the  same  vernier  read,  thj£ 
mean  of  the  two  readings  will  eliminate  the  eccentricity.  For 
it  is  clear  that  the  line  of  the  verniers  will  in  each  case  make 
equal  angles  with  the  line  of  zero  eccentricity  EF,  and  hence 
s  have  the  same  value  with  opposite  sign.  In  other  words, 
since  in  equation  (i)  sin.  (E-\-A)  will  be  positive,  and 
sin.  (E-\-A-\- 180°)  negative,  £  will  have  equal  values  of 
opposite  signs,  and,  therefore,  in  a  mean  of  values  will  disap- 
pear. 


OF     T11K     ENGINEERS     TRANSIT.  51 

We  may  also  apply  equation  (i)  to  the  readings  A'  and  />' 
and  write 

)  (3) 


7-"=/>'+y.sm.  (£+ff)  (4) 

By  taking  the  mean  of  these  two  readings  as  thus  expressed, 
we  get : 


=  c  ss' 

whence  we  see  that  the  difference  between  the  mean  of  the 
true  readings  and  the  mean  of  the  vernier  readings  decreases 
as  (A  —  E)  approaches  180°,  and  when  (A  —  />)  exactly  equals 
1  80°,  or  when  the  verniers  are  rigorously  180°  apart,  this 
difference  is  nil.  The  mean  of  the  readings  of  two  verniers  or 
microscopes  which  are  1  80°  apart,  therefore,  completely  elimi- 
nates the  error  of  the  eccentricity  of  the  circle. 

In  order  to  comprehend  the  effect  of  even  a  small  displace- 
ment of  the  centre,  let  us  from  equation  (2)  take  the  maxi- 
mum value  of  s,  or 

Maximum  e  =.-  -  - 


and  assume  c  =  0.0003  m-  an^  r  =  3-O  in.     Then  we  have  : 

,,     .  2X0.0003X206265"  // 

Maximum  -s  =  —  —  —  =41.25' 

If  c  had  been  as  great  as  0.003  m-  the  maximum  error  of 
eccentricity  would  have  been  6'  $2.5." 

This  fully  illustrates  the  importance  of  three  things:  (i) 
Correct  designs  of  the  axes  or  "  centres  "  of  the  instrument  ; 
(2)  care  in  adjusting  circle  for  eccentricity;  (3)  the  reading  of 
both  verniers  or  microscopes  in  the  higher  classes  of  work. 

The  error  of  eccentricity  of  circles  as  here  treated,  is  really 
made  up  of  two  mechanical  errors,  viz.  :  (i)  Inaccurate  cen- 
tering of  the  circle  on  its  axis  or  "  centre  "  and  (2)  ellipticity 


52  THEORY     OF     THE     ERRORS 

of  the  "  centres  "  themselves.  Moreover  there  arises  in  some 
designs  of  "  centres,"  as  elsewhere  in  this  Manual  already  inti- 
mated, a  wear  of  "  centres  "  which  produces  a  serious  eccen- 
tricity, and  which  cannot  be  remedied  mechanically  except  by 
furnishing  the  instrument  with  new  "centres." 

QUEEN  &  Co.  have  selected  a  design  of  "  centres  "  in  which 
wear  is  not  likely  to  introduce  an  appreciable  error  of  eccen- 
tricity. The  design  is  such  also  as  to  allow  the  nicest  adjust- 
ment for  eccentricity  to  be  accomplished  with  mechanical 
certainty.  It  is  therefore  only  incumbent  on  the  engineer  to 
read  both  verniers  or  microscopes  in  the  finer  classes  of  work. 

THE   ERROR   OF   ECCENTRICITY   OF   THE 

VERNIERS. 

We  have  hitherto  assumed  that  the  zeros  of  the  verniers  or 
microscopes  are  exactly  1 80°  apart.  This  may  not  be  the  case, 
and  if  it  is  not,  we  have  what  may  be  termed  eccentricity  of  the 
verniers.  The  eccentricity  of  the  verniers  is  the  perpendicular 
distance  between  the  centre  of  the  alidade  and  the  straight 

o 

line  joining  the  zero  of  the  verniers,  and  is  in  Fig.  31. repre- 
sented by  C  V.  The  effective  error  it  produces  is  a  constant 


180° 


£ 

Fig.  3*. 

one,  represented  by  the  angle  a.  The  effective  error  of  eccen- 
tricity e,  is,  on  the  other  hand,  as  already  shown,  a  variable 
one.  If  then,  the  zero  of  the  verniers  or  microscopes  are  not 


OF    THK     ENGINEERS    TRANSIT.  53 

accurately  1  80°  apart,  but  make  an  angle  of  i8o°-}-«,  so  that, 
the  eccentricity  of  the  circle  for  the  moment  out  of  question, 
B'  —  A'+  i8o°  +  «,  and  we  may  then  find  from  equations  (3) 
and  (4)  for  the  entire  difference  of  reading  between  the  two 
verniers,  or  B  —  A  —  180°=  o. 

(5) 


Considering  the  alidade  turned  from  its  o°  position  respect- 
ively through  the  angles  90°,  180°,  and  270°,  we  would  have 
for  these  four  respective  values  of  A  the  following  values  of  o  : 

.E.  (6) 


whence  we  find 


dl  =  a  +  2C  s  cos.  E.  (;) 

•N  2     €    S  '  Z?  /0\ 

o.2  =  o.  —  —      -  sin.  h.  (8) 


2  e  s  r*  /  \ 

3  =  a  —          -  cos.  h.  (9) 


a  =  ^L+  ''  i  +  ''-  +  f\  =  the  mean  of  all  the  3's.         (  i  o) 
4 


4-    I     «J  •  /"•  >  > 

2:   __  sin.  h.  =o0 — o2 
r 


(12) 

which  determine  a  and  both  c  and  E. 

We  also  see  from  equations  (6)  and  (8)  that 

r)0  =  «-|-£,  and  o.2  =  a  —  s 

o.t-\-o.,  olt  —  o., 

whence  «  =  "  -I—  2   and  £  =  - 
2  2 

The  objection  to  the  use  of  the  last  two  formulae  for  deter- 
mining a  and  £  are  that  but  two  differences  are  employed,  and 
hence  errors  of  observation  and  of  graduation  may  make  the 
result  uncertain.  The  only  complete  method  for  determining 
a  and  s,  free  from  complication  with  errors  of  graduation  and 


54  THEORY     OF     THE     ERRORS 

observation,  is  to  determine  a  large  number  of  d's  for  different 
direct  and  reversed  positions  of  the  alidade,  and  then  treat  the 
results  of  the  observations  according  to  the  well-known  method 
of  Least  Squares.  For  such  treatment  of  the  subject  our 
readers  are  referred  to  standard  treatises  on  Practical  Astron- 
omy and  Geodesy.  Equations  (10),  (11),  and  (12),  however, 
enable  us  for  many  practical  purposes  to  derive  fairly  reliable 
values  of  a  and  e  by  simply  making  four  sets  of  observations 
at  intervals  of  90°  of  the  differences  of  the  vernier  or  micro- 
scope readings. 


THE  ERRORS  OF  GRADUATION. 

The  errors  of  graduation,  unless  of  the  coarsest  sort,  can- 
not be  investigated  until  the  effect  of  eccentricity  of  the  circle 
and  of  the  vernier  has  been  ascertained.  After  determining 
the  value  of  the  eccentricity  of  the  circle  and  computing  its 
effect  on  the  division  whose  graduation  error  is  to  be  found, 
the  outstanding  differences,  allowing  for  the  constant  deviation 
of  the  verniers  from  the  required  180°,  are  to  be  attributed  to 
graduation  and  observation  errors.  The  errors  of  graduation 
are  divided  into  two  classes  :  (i)  Those  which  are  of  a  periodic 
character,  and  (2)  those  which  are  of  an  accidental  character. 
The,  former  depend  upon  slow  changes  during  graduation  in 
the  temperature  of  the  engine,  or  in  the  condition  of  the  cut- 
ting tool.  The  latter  are  not  dependent  on  known  conditions, 
and  being  as  likely  negative  as  positive,  are  classed  as  acci- 
dental. It  is  usually  found  in  well-graduated  circles  that  the 
major  errors  of  graduation  are  of  the  first  class  and  may  be 
expressed  as  a  periodic  function  of  the  varying  angle. 

Instead  of  using  the  distance  apart  of  the  two  vernier  zeros 
as  the  standard  angle,  the  length  of  the  vernier  may  be  used 
as  a  test  when  successively  applied  round  the  circle,  and  read 
by  means  of  the  excess  graduations  of  the  vernier.  The  ef- 
fect of  the  eccentricity  of  the  circle  on  the  length  of  the  ver- 
nier, must,  in  this  case,  be  computed  and  duly  allowed  for 
before  errors  of  graduation  as  such  can  be  noted.  For  a 


oi-    Tin-     ENGINEERS    TRANSIT.  55 

complete  discussion  of  this  subject  we  refer  the  reader  to  the 
/  'ermessungskuHtU  of  Jordan,  and  to  the  treatises  on  Practical 
Astronomy  of  Chauvenet,  Briinnow,  and  Sawitsch. 

The  errors  of  graduation,  whether  periodic  or  accidental,, 
when  not  known,  are  best  eliminated  by  combining  a  number 
of  readings  at  different  parts  of  the  circle  by  Bessel's  method 
of  Reiteration.  This  method  is  to  be  carefully  distinguished 
from  Borda's  method  of  Repetition,  whicn  is  no  longer  in  favor 
among  the  most  scientific  observers,  and  therefore  not  here 
described.  The  method  of  reiteration  consists  in  systematic- 
ally and  by  equal  arcs  displacing  the  zero  of  the  circle  with 
respect  to  the  verniers  or  microscopes,  so  as  to  pass  through 
an  entire  circumference,  or,  in  the  case  of  two  verniers,  simply 
through  a  semi-circumference.  By  thus  giving  the  circle  a 
number  of  equi-distant  positions  and  taking  the  mean  of  all 
the  observed  readings,  the  periodic  errors  of  graduation  will 
be  completely  eliminated  by  compensation,  and  the  accidental 
errors  will,  according  to  the  method  of  Least  Squares,  be  di- 
minished in  the  inverse  ratio  of  the  square  root  of  the  num- 
ber of  reiterations. 


THE  ERRORS  IN  PRACTICAL  WORK. 

The  foregoing  discussion  of  the  axial  and  circle  errors, 
aside  from  its  value  in  suggesting  points  of  construction 
and  adjustments  of  special  importance  to  accuracy  of  work, 
should  also  afford  many  a  hint  to  the  practical  engineer. 
The  limited  space  does  not  permit  us  to  state  either  the 
special  features  of  instruments  or  the  special  programmes  of 
work  whirh  are  in  the  different  cases  required  to  avoid  and 
eliminate  .ill  the  errors.  And  yet  we  may  not  better  close  this 
review  of  the  errors  than  by  drawing  attention  to  several 
points  of  caution  to  be  exercised  in  the  three  most  usual  forms 
of  work  with  the  transit,  viz. :  the  measurement  of  vertical 
angles,  the  laying  out  of  straight  lines,  and  the  measurement 
of  horiio/ital  angles. 


56  THEORY    OF    THE    ERRORS 

VERTICAL  ANGLES  have  their  zero  in  the  horizon,  and  this 
zero  must  be  physically  determined  by  a  level  lying  in  a  plane 
parallel  to  the  graduated  circle  on  which  the  measurements 
are  to  be  made.  This  level,  whether  it  be  a  plate  level,  the 
telescope  level,  or  a  special  level  attached  to  the  vernier  arm, 
should  not  only  (/)  lie  in  a  plane  parallel  to  the  measuring 
circle,  but  (2)  have  a  sensitiveness  comparable  to  the  fineness  of 
the  reading  on  the  circle,  and  (j)  always  in  an  observation  be 
adjusted  to  zero  position  of  bubble  or  else  be  read  for  the 
:small  deviation  of  the  bubble.  If  the  telescope  level  is  used 
the  vertical  angle  is  simply  the  difference  of  readings  on  the 
circle  for  the  zero  position  of  the  bubble  and  for  the  pointing. 

The  error  of  vertical  axis,  or  the  deviation  of  this  axis  from 
the  vertical,  may  affect  the  measurement  to  the  whole  amount. 
Both  the  error  of  adjustment  of  the  plate  level  and  the  index 
error  (see  sixth  adjustment  in  article  on  ''Adjustments  ")  can 
be  eliminated  by  striking  the  mean  of  the  measures  of  the 
angle  taken  with  the  telescope  both  in  the  direct  and  in  the 
reverse  or  transited  position,  provided  the  alidade  is  carefully 
releveled  after  being  revolved  180°.  The  errors  of  eccentricity 
are  eliminated  by  reading  both  verniers  or  microscopes,  if  there 
be  two.  Transiting  and  two  verniers,  however,  require  a  com- 
plete circle.  For  an  arc  of  a  circle  with  one  vernier,  the  ad- 
justments must  be  relied  on.  The  eccentricity  may,  for  small 
angles,  be  considered  constant,  and,  if  the  "  fourth  adjustment  " 
has  been  accurately  made,  it  is  eliminated  by  taking  the  differ- 
ence of  the  readings  for  bubble  at  zero  and  for  the  pointing. 
The  graduation  errors  can  only  be  eliminated  by  using  an  en- 
tire circle,  capable  of  being  shifted  on  its  axis.  The  method 
of  reiteration  of  the  angle  may  then  be  employed. 

QUEEN  &  Co.  desire  engineers,  when  special  accuracy  is  re-* 
quired  in  vertical  angles,  to  indicate  the  grade  of  accuracy  to 
be  attained.     They  will  then  be  able  to  recommend  a  design 
of  instrument  in  every  particular   suitable    to    the    kind  of 
work. 

STRAIGHT  LINES  can  be  prolonged  accurately  only  with  good 
instruments  and  the  most  careful  attention.  Here  the  secret 


; 
OF  THE  ENGINEER'S  TRANSIT.  57 

of  the  elimination  of  errors  is  so  to  arrange  the  programme  of 
work  as  to  distribute  the  errors  symmetrically  with  respect  to 
the  proposed  line.  If  a  circumpolar  star  is  observed  for  the 
direction  of  the  meridian  it  is  therefore  important  that  the  ob- 
servations both  as  to  number  and  character,  be  arranged  sym- 
metrically with  regard  to  the  time  of  transit,  or  the  time  of 
elongation,  as  the  case  may  be. 

If  the  pointings  for  a  line  are  all  horizontal,  and  the  line  is 
to  be  prolonged  by  transiting  the  telescope,  or  turning  it  over 
on  its  horizontal  axis,  the  constant  collimation  error  will  enter 
with  double  its  value.  If,  secondly,  one  of  the  pointings  is  at 
an  angle  as  in  the  case  of  determining  the  direction  of  a  cir- 
cumpolar star,  the  errors  of  collimation,  of  the  horizontal 
axis,  and  of  verticality  of  the  vertical  axis,  may  all  enter  the 
result.  Particularly  would  the  error  of  verticality,  due  to  the 
level  at  right  angles  to  the  line,  be  serious  and  necessitate  at- 
tention to  the  sensitiveness,  adjustment,  and  reading  of  the 
level  lying  in  that  direction. 

A  line  may  be  prolonged  so  as  to  eliminate  all  these  errors 
by  setting  up  over  the  forward  point,  leveling  cross-level,  bi- 
secting rear  point,  transiting  telescope,  and  locating  the  re- 
quired point;  and  then  revolving  the  alidade  180°  and  repeat- 
ing the  operation  and  taking  the  mean  position  between  the 
two  located  points  as  the  true  required  point. 

QUEEN  &  Co.  make  instruments  especially  adapted  for  run- 
ning straight  lines,  including  tunnel  work.  These  are  pro- 
vided with  powerful  telescopes,  delicate  striding  levels,  and  are 
reversible  on  their  horizontal  axes. 

HORIZONTAL  ANGLES,  including  the  horizontal  straight  angles 
just  referred  to,  are  those  most  frequently  measured  in  prac- 
tical work,  and  the  errors  to  which  they  are  liable  have,  there- 
fore, been  fully  discussed. 

The  accurate  measurement  of  a  horizontal  angle  may  pro- 
ceed as  follows  :  Test  the  adjustments,  particularly  that  of  the 
levels.  Level  carefully.  Set  vernier  A  accurately  to  zero,  and 
with  clamped  alidade  turn  the  telescope  upon  the  left-hand 
object.  Clamp  the  circle  and  bisect  by  means  of  low%r,  or 


58      THEORY  OF  THE  ERRORS  OF  THE  ENGINEER  S  TRANSIT. 

circle,  tangent  screw.  Vernier  A  still  being  at  zero,  read  ver- 
nier B.  Now  unclamp  alidade  and  turn  telescope  upon  right- 
hand  object.  Clamp  alidade  and  bisect  by  means  of  upper, 
or  alidade,  tangent  screw.  Read  both  verniers  accurately. 
The  difference  between  the  means  of  the  vernier  readings  is 
the  measurement  of  the  angle  for  the  telescope  in  direct  posi- 
tion. Now  transiting  the  telescope,  direct  the  telescope  to 
left-hand  object  and  shift  the  circle  a  fraction  of  360°  from  its 
initial  position  and  repeat  the  foregoing  programme  for  this 
reversed  position  of  the  telescope.  The  mean  of  the  results  for 
direct  and  reversed  telescope  is  the  angle  freed  from  the  errors 
of  collimation,  horizontal  axis,  from  error  of  verticality  (as 
far  as  possible),  and  from  eccentricities  of  telescope,  verniers, 

and   circle.     Reiteration   of   this  process  by  shifting  —  th  of 

n 

360°  if  the  angle  is  to  be  measured  n  times  with  each  posi- 
tion of  telescope,  will  give  a  mean  result  measurably  free 
from  graduation  errors. 

A  PRACTICAL  INFERENCE  of  great  importance  alike  to  those 
who  use,  and  to  those  who  make  engineering  and  geodetic  in- 
struments follows  from  the  foregoing  Theory  of  the  Errors  of 
the  Universal  Altazimuth.  It  is  that  since  in  each  of  the  three 
main  classes  of  work  adverted  to,  the  errors  to  be  feared  and 
if  possible,  avoided  or  eliminated,  are  of  a  peculiar  type,  there- 
fore a  peculiar  type  of  instrument  ought  to  be  designed  to 
meet  the  highest -demands  in  each  class  of  work.  An  instru- 
ment maybe  designed  mainly  for  measuring  horizontal  angles 
or  for  prolonging  straight  lines,  or  for  measuring  vertical 
angles  and  the  particular  purpose,  together  with  the  degree  of 
accuracy  to  be  met  in  the  special  class  of  work,  will,  withjthe 
expert  maker,  determine  every  detail  of  the  instrument. 

QUEEN  &  Co.,  accordingly,  stand  ready  not  only  to  meet 
the  demands  for  good  universal  transits  suited  to  all  ordinary 
practical  requirements,  but  also  to  furnish  those  special  instru- 
ments required  in  the  more  difficult  engineering  and  geodetic 
operations. 


QUEEN"  LIGHT  MOUNTAIN  TRANSIT. 


A  1508. 


THE  GRADUATED  CIRCLES 

OF  THE 

ENGINEER'S  TRANSIT. 


THE  GRADUATIONS. 

THE  accurate  graduation  of  circles  is  one  of  the  most 
delicate  operations  in  the  mechanical  arts.  It  requires 
not  only  machinery  of  unquestioned  certainty  of  condition  and 
of  movement,  but  constancy  of  temperature  during  the  entire 
process,  and,  even  with  purely  automatic  machines,  the  most 
alert  and  skillful  attention.  QUEEN  &  Co.  have  in  their  works 
two  large  dividing  engines  adapted  to  the  graduation  of  the 
different  classes  of  circles  required  for  the  astronomical  and 
engineering  instruments  they  make.  Every  attention  is  given 
not  only  to  accurate  centering,  correct  spacing,  and  to  an  even 
performance  of  the  graduating  engine,  but  to  the  final  finish 
and  numbering  of  the  graduated  circle,  so  as  to  secure  ease 
and  certainty,  as  well  as  accuracy,  in  the  reading. 

Errors  of  graduation,  though  never  so  small,  are  to  be  found 
in  every  circle  yet  graduated  by  human  skill.  The  problem 
is,  then,  one  of  degree  of  error.  With  QUEEN  &  Co.  the  aim 
is  to  furnish  graduated  circles  whose  error3  may  safely  be  re- 
garded as  infinitesimal,  except  in  astronomical  and  geodetic 
work  of  the  highest  class.  In  this  most  refined  class  of  work- 
there  is,  as  the  most  noted  observers  have  again  and  again 
demonstrated,  absolutely  no  recourse  excepting  a  complete 
examination  of  the  graduation,  and  the  preparation  of  a  table 
of  corrections.  For  a  further  reference  to  this  subject  consult 
"Errors  of  Graduation  "  in  the  article  of  this  Manual  entitled 
"  The  Mathematical  Theory  of  the  Errors  of  the  Engineer's 
Transit? 

59 


60  THE    GRADUATED    CIRCLES 

MEANS  FOR  READING  SUBDIVISIONS  OF 
CIRCLES. 

The  devices  chiefly  employed  for  reading  the  subdivisions  of 
circles  are  the  Vernier  and  the  Micrometer  Reading  Micro- 
scope. Of  these  the  former,  on  account  of  its  simplicity,  cheap- 
ness, and  sufficient  accuracy,  is  almost  exclusively  used  in 
engineering  instruments.  It  is  only  in  high-class  geodetic 
instruments  that  the  use  of  the  Micrometer  Reading  Micro- 
scope is  at  all  warranted.  The  Estimation  Microscope,  referred 
to  further  on,  is,  however,  coming  into  favor  for  the  finer  read- 
ings where  rapidity  of  work  is  desirable. 

THE  VERNIER— ITS  THEORY  AND  FORMS. 

The  Vernier  was  first  described  in  a  work  entitled  La  Con- 
struction, L usage  et  les  Proprietes  du  Quadrant  Nouveau  dc 
MatJicmatiques,  etc.,  du  Pierre  Vernier,  Bruxelles,  idji.  The 
same  appliance  is  by  the  Germans  called  a  "  Nonius"  although 
the  instrument  described  by  the  Portuguese  "  Nunnes,"  or 
"  Nonius,"  in  1542,  was  in  principle  essentially  different. 

The  Vernier  is  an  accessory  divided  scale  placed  alongside 
the  main  divided  scale,  and  permits  the  subdivisions  of  the  main 
scale  to  be  read  by  noting  the  difference  in  length  of  the 
Vernier  and  the  Scale  divisions.  In  Circular  Instruments  the 
Vernier  is,  of  course,  an  arc  concentric  with  the  main  divided 
circle,  and  so  graduated  that  the  ratio  of  the  divisions  of  the 
Vernier  to  those  of  the  Circle  may  be  the  one  required  to 
give  the  reading  to  the  subdivision  intended.  An  easy  mathe- 
matical discussion  will  make  this  clear  in  every  detail. 

The  general  theory  of  the  Vernier,  forming  the  basis  for  the 
construction  of  all  verniers  may  be  stated,  as  follows : 

Let  s  =  The  value  of  a  division  of  the  main  Scale  or  Circle. 
v  =  The  value  of  a  division  of  the  Vernier. 

*-f'1 

or     >5=  The  "  least  count,"  or  smallest  subdivision  of  the 

v      s  )  Scale  or  Circle  to  be  read  by  the  Vernier. 

n  =  The  number  of  divisions  of  the  Vernier  correspond- 
ing to  (//  — /),  or  («  +  /)  divisions  of  the  Scale  or 
Circle. 


OF  THE  ENGINEER'S  TRANSIT.  61 

The  Vernier  is  then  always  so  graduated  as  to  make 

ni'  =  (n±i)s.  (l) 

If  the  upper  sign  is  used,  then  any  single  vernier  division  is 
smaller  than  a  single  scale  or  circle  division,  and  the  vernier  is 
a  direct  reading  vernier  with  divisions  numbered  in  the  same 
direction  as  the  circle  is  read.  If  the  lower  sign  is  used  a 
vernier  division  is  larger  than  a  scale  or  circle  division,  and 
the  vernier  is  a  retrograde  vernier,  reading  and  numbered  in 
the  direction  opposite  to  the  reading  on  the  circle.  From 
equation  (i)  we  easily  derive  the  following  sets  of  equations 
for  the  two  classes  of  verniers  : 

FOR  DIRECT  VERNIERS.  FOR  RETROGRADE  VERNIERS. 

«  =  -*-.  (2)          »  =  _£-.  (5) 

S V  V S     . 

H — r  /  \  n-\-i  tz\ 

v  =   ~—s.  '  (3)  *  =  -X-A  (6) 

s  —  v=~s.  (4)          ,,—s  =  -Ls.  (7) 

The  direct  Reading-  Vernier,  being  the  one  almost  exclusively 
in  use,  we  need  illustrate  only  the  first  set  of  formulae  by 
means  of  a  few  examples.  Suppose  a  circle  divided  to  20', 
and  that  it  is  desired  to  read  it  to  30",  then  from  equation  (2) 

we  see  that  n  = =  40,  or  40  vernier  divisions   must  be 

3° 
made  equal  to  (40 —  i),  or  39,  scale  divisions,  in  order  to  make 

30"  the  least  count.    Also  from  (3),  v=  ¥>X  1200"  =  19'  30" 

40  » 

=  value  of  one  vernier  division  ;  or,  in  other  words,  each  vernier 
division  will  be  30"  smaller  than  the  scale  division,  and  "hence 
if  a  given  vernier  division  coincides,  or  forms  the  same  straight 
line  with  a  scale  division,  it  shows  how  many  times  30"  the 
zero  of  the  vernier  has  passed  the  scale  division  immediately 

preceding    it.      Also  from  (4),  j  —  v=~-  1200"=  30"=  the 

4°. 
least  count.     The  accompanying  Fig.  33,  represents  a  double 


62  THE    GRADUATED    CIRCLES 

direct   reading  vernier,  applied  to   a  circle  with   20'  divisions, 
and  reading  to  30''. 

The  reading  of  a  circle  by  means  of  a  vernier  consists  of 
two  operations.  First,  to  find  beyond  what  graduation  the 
zero  of  the  vernier  has  passed ;  second,  to  read  the  vernier 
itself  for  coincidence.  We  always  read  the  vernier  in  the  di- 
rection the  numbering  is  inclined.  If  we  read  in  the  direction 
of  the  upper  numbering,  we  use  the  right-hand  vernier,  as  fol- 
lows :  First,  the  zero  of  the  vernier  has  passed  I  °  and  20'  be- 
yond the  1 10°  mark,  and  the  first  reading  would  therefore  be 
iii°  20'.  Second,  we  find  that  the  25th  division  of  the  ver- 
nier is  in  coincidence  with  a  division  of  the  limb,  and  as  the 
least  count  is  30",  this  would  mean  12'  30";  adding  this  to 
ui°  20',  we  have  1 1 1°  32'  30"  for  the  reading. 


Similarly,  if  we  are  reading  in  the  direction  of  the  lower 
numbering,  first  the  rough  reading  is  248°  20' ;  second,  the 
reading  on  the  vernier  is  f  30"  ;  the  sum  of  the  two,  248° 

27'  3o". 

Practically  the  reading  of  a  vernier  like  the  one  here  figured 
is  made  very  quickly  by  first  taking  up  the  degrees,  and  while 
keeping  in  mind  the  minutes  of  the  circle,  adding  to  these  the 
minutes  and  seconds  of  the  vernier,  the  whole  minutes  being 
indicated  by  the  alternate  long  lines  of  the  vernier.  Thus, 
reading  to  the  right,  the  excess  of  20'  on  the  circle  is  mentally 
added  to  the  reading  of  1 2'  50"  on  the  vernier,  and  the  whole 
reading  1 1 1°  32'  30"  at  once  set  down. 

A  table  illustrating  the  properties  of  the  verniers  employed 
with  the  usual  graduations  of  QUEEN  &  Co.'s  instruments  is 
here  appended.  A  study  of  it  may  prove  useful  to  beginners, 


OF    THE    ENCINKKK  S    TRANSIT.  63 

as  familiarizing  them  with  various  kinds  of  graduations   and 
verniers : 


Vernier. 

s 

n 

n  —  / 

V 

j  —  # 

ft) 

3°' 

30 

29 

29'  oo"       i  ' 

(2) 

20' 

40 

39 

I9/  30" 

30" 

(3) 

I5/ 

30 

29 

14'  30" 

30" 

(4) 

20' 

60 

59 

19'  40"      20" 

(5) 

'5' 

45 

44 

14'  40"        20" 

(6) 

60 

50 

9'  50"      10" 

The  Retrograde  Vernier  is  sometimes  used  on  the  arc  or 
circle  of  the  Engineer's  Compass.  It  is  also  used  in  connec- 
tion with  barometer  scales. 


Fig-  34- 

A    retrograde    double  vernier    of  a  compass   is   shown   in 
Fig.  34,  where  30  vernier  divisions  equal   3 1  of  the  limb  and 

the  limb  is  divided  to  half  "Degrees.     Consequently,  according 

, 

to  formula  (/),?' — s  =  -  -s,  or  the  least  reading  =       X  $o'=i'. 

This  form  of  vernier  is  here  only  one-half  as  long  as  a  double 
direct  vernier.  It  extends  to  15',  and  the  upper  figures  on 
one-half  are  in  a  manner  a  continuation  of  the  lower  ones  on 
the  other  half.  Thus  in  the  figure  the  zero  of  the  vernier 
having  been  moved  to  the  right,  the  lower  figures  of  the  left- 
hand  vernier  are  read  when  the  angle  passed  over  is  less  than 
15';  but  as  more  have  here  been  passed,  the  upper  figures  of 
the  right  hand  are  taken  as  a  continuation,  and  the  reading 
evidently  is,  i°  30'  (limb) 4- 23'  (vernier),=  i°(53'. 


THE    GRADUATED    CIRCLES 


H 


THE  READING  MICROSCOPE— ITS  FORMS, 
THEORY,  AND  ADJUSTMENTS. 

The  Micrometer  Reading  Microscope  is  esteemed  an  essential 
requisite  for  the  highest  class  of  circle  readings.  The  accom- 
panying Fig.  35  shows  a  vertical  section 
of  the  microscope  as  placed  over  the 
graduation.  In  the  common  focus  of 
the  objective  and  eye-piece  at  /MS  formed 
an  image  of  the  division  of  the  limb. 
The  narrow  lane  formed  by  two  parallel 
micrometer  threads,  as  shown  in  Fig.  36, 
is  then,  by  means  of  the  micrometer 
screw,  moved  until  it  centrally  includes 
the  given  division.  The  number  of  whole 
revolutions  of  the  screw  are  counted  by 
means  of  the  notches  seen  in  the  field  of 
view  Fig.  36,  and  the  fraction  of  a  revo- 
lution is  read  off  on  the  graduated  head//. 
The  notches  used  as  counters  are  each 
a  complete  revolution  distant  from  each 
other,  and  each  fifth  one  is  cut  deeper 
v  and  specially  marked.  The  graduated 
head  //of  the  screw  is  usually  divided  into  sixty  divisions  and 
reads  directly  to  seconds,  and  by  estimation  to  tenths  of 
seconds. 

Figures  35  and  36  will,  without  much  further  assistance, 
indicate  the  construction  of  the  micrometer  microscope  in  suf- 
ficient detail.  The  eye-piece  A  B  is  a  positive  one,  and  (ex- 
cept in  determining  the  requisite  magnification  and  definition) 
does  not  enter  into  the  optical  theory  of  the  reading  micrl>- 
scope.  The  micrometer  screw  is  opposed  by  springs,  b  b,  which 
hold  the  slide  a  a,  carrying  the  parallel  threads,  so  that  it 
always  bears  against  one  side  of  the  screw  threads  c  c,  and 
there  is  no  lost  or  dead  motion.  It  is  conducive  to  accuracy, 
nevertheless,  always  to  turn  the  screw  in  only  one  predeter- 
mined direction  before  each  bisection  of  a  division  of  the  limb. 


C 

Fig-  35- 


ol      11I1-.    ENGINEERS    TRANSIT. 


Fig.  36- 

The  optical  theory  of  the  Micrometer  Microscope  is  put  in  sim- 
ple form  as  follows :  Assuming  that  one  revolution  of  the  mi- 
crometer screw  carries  the  set  of  parallel  threads  from  one 
central  position  over  a  division  to  another,  and  letting : 

Sj= Linear  movement  of  these  threads  due  to  one  revolution 
of  screw. 

s2=  Length  of  one   division  of  circle. 

dx=  Distance  of  threads  from  the  mi- 
croscope objective. 

(f.2=  Distance  of  circle  from   the   mi- 
croscope  objective. 

We  have,  according  to  Fig.  37  : 

—+—=*—i     (0,    and  Sl  =  (  '  , 

whence   by  respectively  eliminating 
and  (fl  by  combining  ( i)  and  (2)  we  hav 


=/+V.        (3),   df= 


The  equations  (3)  and  (4)  give  the 
distances  respectively  at  which  the 
threads  and  the  limb  must  be  placed  from  the  microscope  ob- 
jective, provided  the  eye-piece  be  a  positive  one,  as  shown  in 
Fi  *.  35.  An  eye-piece  of  the  Huygenian  sort,  with  its  collec- 
tive lens,  wou'd  introduce  other  considerations. 


66  THE    GRADUATED     CIRCLES 

The  adjustments  of  the  Micrometer  Microscope  may  be  stated 
as  follows : 

1.  The  threads  of  the  microscope  should  be  parallel  to  the 
circle  divisions.     This  is  accomplished  by  turning  the  entire 
microscope  in  its  support 

2.  The  optical  axis  of  the  microscope  should  be  at  right 
angles  to  the  graduated  limb.     This  condition  may  be  tested 
.with  sufficient  accuracy  by  direct  measurements.      A  good 
optical  test  is  the  precise  equality  of  definition  of  a  division  of 
the  limb  as  it  passes  across  the  field. 

3.  The   distances  d±  and  d.2  are   to   be  so  adjusted  that  a 
^whole  number  of  revolutions  of  the  screw  is  equal  to  the  dis- 
tance between  two  consecutive  graduations  of  the  limb.   If  the 
head  of  the  screw  indicates  more  than  a  whole  number  of  revo- 
lutions for  one  division  of  the  limb,  d±  and  d.2  must  be  lessened, 
.i.-e.,  the  objective  brought  nearer  the  threads,  and  the  whole 
microscope  nearer  the  limb.     If  the  head  of  the  screw  indicate 
less  than  a  whole  number  of  revolutions  for  one  division  of 
the  circle,  dl  and  d.2  must  be  increased.     In  each  case  dl  is  first 
lessened  or  increased,  and  then  the  microscope  moved  until 
the  circle  graduations  again  appear  well  defined.    The  changes 
in  dl  and  d2  for  any  given  excess  or  deficit  of  the  screw  read- 
ing, are,  however,  most  certainly  and  accurately  made  by  first 
computing  their  value  by  formulae  easily  derived  from  equa- 
tions (3)  and  (4). 

4.  The  micrometer  screw  should  be  as  nearly  as  possible  a 
perfect  one,  without  inequalities  or  irregularities. 

The  errors  of  the  Reading  Microscope  are  readily  investigated. 
As  in  other  features,  so  here,  although  a  high  grade  of  accuracy 
of  adjustment  is  to  be  expected  from  competent  and  con- 
scientious makers,  there  will  still  be  small  errors  of  adju|t- 
merit  as  well  as  other  errors  arising  from  changes  of  tempera- 
ture and  the  like,  which  have  to  be  determined  and  allowed 
for  in  the  most  refined  classes  of  measurement.  It  is  usually 
sufficient,  even  in  the  best  work,  to  investigate  the  following- 
errors  : 

I.  The  error  of  runs,  or  the  excess  of  a  circle  division  above 
a  whole  number  of  revolutions  of  the  screw  may  be  determined 


OF  THK   i;.v, INKER'S  TRANSIT.  67 

by  measuring  a  number  of  divisions  in  different  parts  of  the 
circle  and  taking  the  mean  so  as  to  eliminate  graduation 
errors.  A  proportional  part  of  this  error  must  be  allowed  for 

in  all  readings.     If  one   division,  for  example,  measures  5-^- 

60 
revolutions,  or  equals  5'-|-i".8,  each  minute  read  off  must  be 

\"  8 

corrected  by  =  —  —  —  or  —  o" '.36.  Only  for  the  highest  ac- 
curacy need  the  error  of  runs  be  determined  at  different  tem- 
peratures and  corrected  for  inequalities  of  the  screw. 

2.  The  errors  of  inequality  of  the  screw  may  be  determined 
by  measuring  some  small  distance,  as  that  between  a  circle 
graduation  and  a  special  graduation,  or  as  that  of  the  distance 
apart  of  the  two  micrometer  hairs,  if  this  is  an  aliquot  part  of 
a  division.  The  mean  of  many  such  measures  is  then  taken 
as  the  standard  value  for  the  preparation  of  a  table  of  correc- 
tions for  the  inequality  of  the  screw.  These  corrections 
should  be  allowed  for  before  the  error  of  runs  is  determined. 
But  in  well-made  screws  the  errors  of  inequality  are  small 
enough  to  be  entirely  neglected. 

The  Estimation  Microscope,  as  recently  applied  to  the  reading 
of  the  circles  of  the  theodolites,  dispenses  with  the  micrometer 
screw,   and   in    its  place    has    a  fixed  scale  divided  on  glass. 
It  is  on  this   account  sometimes  called  the  Scale  Microscope. 
The  accompanying  figure  shows  a  circle  divided  to  10',  as  ap- 
pearing under  an  estimation  micro- 
scope.    The  ten  divisions  marked 
o,  5,  10  belong  to  the   microscope, 
and  are  together  equal  in  length  to 
10'.     The  zero  is  3',  and,  we  esti- 
mate, o'./  more,  beyond  the  40°  10' 
mark,  and    hence  the    reading    is 
40°    1 3'7  =  40°    13'   42".         This 
method   lacks  the  accuracy  of  the 
micrometer  microscope,  but  has  the 
advantage  of  rapidity.    Single  read- 
ings can  be  made  by  this  means  with  a  probable  error  of  about 
=b  5".     The  ordinary  graduation  intended  for  vernier  reading 


68     THE  GRADUATED  CIRCLES  OF  THE  ENGINEER'S  TRANSIT. 

appears  too  heavy  under  the  microscope  for  the  most  accurate 
reading  by  estimation,  and  hence,  when  desired,  QUEEN  &  Co. 
make  a  specially  delicate  graduation,  suited  to  the  demands  of 
the  estimation  method. 

THE  ADJUSTMENTS  of  the  Estimation  Microscope  are  simi- 
lar to  those  of  the  Micrometer  Microscope.  The  scale  and 
the  image  of  the  graduation  must  both  appear  with  good  defi- 
nition. The  divisions  of  the  scale  must  be  parallel  to  the  di- 
visions of  the  graduation  circle,  and  the  whole  microscope 
must  have  its  axis  at  right  angles  to  the  plane  of  the  circle. 
The  interval  of  the  scale  must  also  correspond  with  that  of 
the  graduations,  and  there  may  hence  also,  from  lack  of  ac- 
curate correspondence,  be  an  error  similar  to  the  error  of  runs 
of  the  micrometer  microscope. 

THE  RELATIVE  ACCURACY  of  verniers  and  micrometer  read- 
ing microscopes  has  been  investigated  by  Bauernfeind,  who 
concludes  that  for  circles  of  five  inches  and  over  the  micro- 
scope is  the  more  accurate,  but  that  the  time  expended  in 
adjusting  and  reading  the  microscope  is  very  much  greater 
than  for  the  vernier.  Well-made  verniers,  read  with  good  illu- 
mination and  with  the  axis  of  the  eye  in  the  same  plane  as  the 
coinciding  divisions,  may  produce  results  of  a  high  order.  But 
the  highest  accuracy  with  large  circles  can  only  be  attained 
by  means  of  the  micrometer  microscope.  It  is  probable,  how- 
ever, that  taking  both  time  and  accuracy  into  consideration, 
the  estimation  or  scale  microscope  is  often  to  be  preferred  to 
either  the  vernier  or  micrometer  microscope. 

A  RECENT  PLAN  adopted  to  obviate  the  necessity  for  adjust- 
ing the  microscope  to  correspondence  with  the  graduations  is, 
to  carry  the  direct  graduation  of  the  circle  down  to  such  a 
degree  of  fineness  that  it  is  only  necessary  to  use  a  single 
thread  in  the  microscope  as  a  means  of  estimating  further  sub- 
divisions. 

QUEEN  &  Co.  believing  that  there  is  room  for  materially 
extending  the  accuracy  of  graduation  and  the  convenience  of 
circle  reading  as  applied  to  engineering  and  geodetic  instru- 
ments, make  it  their-  constant  aim  to  be  abreast  of  the  highest 
modern  science  and  skill  in  this  work. 


"QUEEN"  RECONNOISSANCE  TRANSIT. 


A  1518. 


Price,  $125.00 


THE  SPIRIT  LEVELS 

OF 

ENGINEERING  INSTRUMENTS. 


AS  an  essential  part  of  nearly  every  important  engineering 
instrument,  the  spirit  level  deserves  special  considera- 
tion in  respect  of  its  theory,  construction,  and  use.  This  the  more 
on  account  of  the  apparent  indifference  among  the  engineering 
fraternity,  and  consequently  among  makers  themselves,  regard- 
ing the  performance  of  the  levels  of  instruments.  Neglect  of 
the  subject  is  also  shared  by  the  standard  American  treatises 
on  surveying.  It  is  therefore  deemed  important  to  draw  the 
special  attention  of  the  engineer  to  this  essential  part,  in  the 
hope  that  scientific  makers  may  be  fairly  encouraged  to  fur- 
nish instruments  suited,  as  well  in  this,  as  in  other  respects,  to 
reliable  work. 

Spirit  Levels  are  the  most  sensitive,  and  therefore  the  most 
important,  appliances  for  practically  determining  horizontal  or 
vertical  planes  and  for  measuring  small  angles.  They  replace 
and  far  excel  the  plumb  line  as  formerly  used  for  the  same  pur- 
pose. They  are  of  two  kinds,  cylindrical  levels,  and  circular 
or  box  levels. 

The  Cylindrical  Level  consists  of  a  cylindrical  glass  tube, 
with  the  inner  surface  ground  to  circular  curvature,  and,  being 
nearly  filled  with  a  very  mobile  liquid  like  alcohol  or  ether, 
sealed  at  both  ends.  The  part  of  the  tube  not  filled  by  the 
liquid  is  occupied  by  its  vapor.  A  scale  of  equal  divisions  is 
usually  either  engraved  on  the  outside  of  the  glass  tube  or  on  a 
metallic  strip  placed  near  the  level,  and  in  the  plane  in  which 
the  level  is  to  be  used. 

The  geometric  features  of  the  cylindrical  level  will  be  under- 
stood from  Fig.  39. 

The  curve  in  any  plane,  as  that  represented  by  this  sectional 

69 


70  THE    SPIRIT    LEVELS    OF 

view,  is  the  arc  of  a  circle  whose  chord  is  either  AB,  or  CD. 

The  "axis  of  the  level  "  is  a 

line  parallel  to  the    chord 

AB,    as    the    medial     axis 

MM,  or    it  is  the  tangent, 

7T,  to  the  arc  at  the  point 

0.     While  the  axis  of  the 

level  may  indeed  be  a  line 

parallel  to  any  tangent  of 

the  curve,  the  axis  is  by  common   consent  taken  as  that  line 

which  is,  or  is  parallel  to,  the  tangent  of  the   curve   at  trie 

marked  zero.      The   "  plane   of  the   level  "   is  the   horizontal 

plane  containing  this  axis.     The  central  point,  (9,  of  the  arc 

which  is  occupied  by  the  centre  of  the  bubble  when  the  axis  is 

horizontal  is  called  "  the  zero  point  "  of  the  level.     The  grad- 

uated scale  should  read  both  ways  from  this  zero.     The  prac- 

tice in  vogue  among  some  makers  of  leaving  the  central  por- 

tions of  the  level  without  graduations  is  as  unscientific  and 

inconvenient  as  it  is  antiquated. 

The    theory  of  the  Spirit  Level    may    be  briefly  stated  as 
follows  : 

Let,  /  =  Amount  of  any  given  bubble  displacement  expressed 

in  linear  units. 
r  =  Radius  of  curvature  of  inner  surface  of  the  bubble 

tube,  measured  in  the  same  linear  unit. 
Tcr  =  Semi-circumference  of  this  circle. 
;/  =  Number  of  scale  divisions  the  bubble  is  displaced. 
d  =  Value  in  seconds  of  arc  of  each  scale  division. 
nd  =  The  total  displacement,  expressed  in  seconds  of 

arc. 
Then  evidently  we  have  the  following  relation  • 


i  80 


That  is,  the  linear  displacement  of  the  bubble  is  to  the  whole 
length  of  the  semi-circumference,  as  the  number  of  seconds  of 


KN<;iNKKRIN<;     1  NSTIU'M  KNTS.  •  71 

arc  of  bubble  displacement   is  t<>  the  total  number  of  seconds 
in  the  semi-circumference.      From  equation  (i)\ve  derive:  9 


/  —  (->}•      r=  3    (i)-     d—  D    (A\ 

~  206265 '   Wl  »</  *r 

Formula  (2)  gives  the  linear  bubble  displacement  in  terms  of 
the  radius  of  curvature,  the  seconds  of  arc  this  displacement  is 
to  represent,  and  the  number  of  seconds  in  a  radian.  Formula 
(3)  enables  one  to  derive  the  radius  of  curvature  from  the  lin- 
ear displacement  of  bubble,  its  value  in  seconds,  and  the  num- 
ber of  seconds  in  a  radian  ;  and  equation  (4)  expresses  the  arc 
value  of  a  division  in  terms  of  the  radius,  the  number  of  seconds 
in  a  radian,  and  the  linear  value  of  a  division. 

The  sensitiveness  of  a  level,  or  the  given  bubble  displace- 
ment corresponding  to  a  given  angle,  varies  directly  as  the 
radius  of  curvature.  Hence  levels  ground  to  a  short  radius 
give  scarcely  any  displacement  of  bubble  for  a  small  variation 
of  angle,  while  those  of  sufficiently  long  radius  may  be  made 
to  show  an  appreciable  displacement  of  bubble  for  an  angular 
value  of  but  a  fraction  of  a  second  of  arc.  The  sensitiveness 
of  levels  is  usually  stated  as  so  much  deviation  of  bubble  per 
single  division  of  one  French  line  of  2.26  mm.  in  length.  It 
varies  from  5'  per  division  for  circular  levels  applied  to  level- 
ing rods,  to  5"  per  division  or  less,  in  levels  applied  to  the 
finer  leveling  instruments,  and  to  2"  or  less  in  those  applied 
to  astronomical  instruments. 

The  reading  of  the  bubble  requires  the  position  of  both  ends 
to  be  noted  with  respect  to  the  scale.  Only  the  roughest  work 
allows  the  position  of  the  centre  of  the  bubble  to  be  esti- 
mated. The  estimations  of  the  positions  of  the  ends  of  the 
bubble  are  usually  expressed  in  divisions  and  tenths  of  divisions, 
counting  from  the  zero  of  the  scale  in  the  middle  of  the  tube. 
Readings  of  the  bubble  for  the  left-end,  13.8,  and  for  the  right- 
end,  1 6.2,  mean  that  the  half-length  of  the  bubble  is  15  divis- 
ions, and  its  middle  displaced  1.2  divisions  to  the  right. 

In  the  use  of  very  delicate  levels  it  is  not  always  convenient 


72  THE    SPIRIT    LEVELS    OF 

to  read  from  the  marked  zero,  and  an  assumed  zero  determined 
by  observation  of  the  error  of  adjustment  may  then  be  used. 

The  Adjustments  of  the  Cylindrical  Level  are  two  in  number. 
The  first  requirement  is  that  the  axis  of  the  level  and  the  axis 
of  the  instrument  shall  lie  in  the  same  plane.  Any  other 
position  of  the  level-axis  is  said  to  be  a  crosswise  position. 
The  second  requirement  is  that  the  physical  line  or  plane 
formed  by  the  supporting  base  of  the  level  shall  be  parallel 
to  the  level-axis,  or  parallel  to  the  tangent  of  the  level- 
curve  at  the  zero  of  its  graduation.  Both  these  adjustments 
will  be  fully  described  in  the  subsequent  explanation  of  the 
use  of  a  striding  or  other  fine  level. 

The  making  of  a  fine  level  requires  much  skill  and  patience. 
It  includes  principally  the  grinding  of  the  curve  and  the  seal- 
ing of  the  tube. 

The  grinding  of  the  inner  surface  to  the  requisite  curvature 
would  seem  an  easy  operation,  but  practically  it  is  found  that 
the  grinding  does  not  always  bear  the  test  of  the  level-trier. 
Irregularities  of  curvature  are  a  fatal  blemish  and  can  only  be 
obviated  by  costly  skill. 

The  sealing  of  the  tube  is  also  not  a  simple  matter.  Leak- 
age follows  upon  nearly  all  methods  except  the  hermetic. 
The  plan  of  electrolytically  depositing  copper  on  the  stop- 
pered ends  has,  however,  also  proved  a  success. 

The  brass  case  usually  supporting  and  largely  inclosing  the 
level  tube  should  be  separated  from  it  by  some  good  non-con- 
ductor of  heat.  Sometimes,  to  protect  the  delicate  level  from 
rapid  temperature  changes,  the  case  is  a  double  one,  inclosing 
air.  Another  requisite  is  that  the  level  be  so  fastened  in  its$ 
case  as  not  to  suffer  stress  from  changes  in  temperature. 

The  Chambered  Level  is  one  provided  at  one  end  with  a  par- 
tition, which  allows  part  of  the  bubble,  if  too  long,  to  be  re- 
moved and  confined  apart.  This  device  is  only  required  in 
very  large  levels,  where  the  highest  sensitiveness  and  quick- 
ness of  action  are  required. 

The  Double  Level  is  a  cylindrical  level  ground  to  curve  above 


ENGINEERING    INSTRUMENTS.  73 

and  below,  and  provided  with  two  corresponding  scales.  When 
attached  to  a  telescope  it  consequently  enables  leveling  to  be 
done  in  two  positions.  The  complicated  errors  to  which  it  is 
liable,  together  with  its  costliness,  make  it,  however,  of  doubt- 
ful value.  It  seems  better  always  to  use  two  levels  instead  of 
the  double  level,  when  it  is  necessary  to  keep  the  telescope 
level,  both  in  a  direct  and  in  a  reverse  position. 

The  Circular  Level,  or  box  level,  consists  of  a  small  metallic 
vessel  nearly  filled  with  mobile  liquid  and  sealed  with  a  glass 
covering  whose  inner  surface  has  been  ground  to  a  spherical 
surface.  This  level  is  usually  of  but  a  small  sensitiveness, 
the  angular  value  of  a  deviation  of  the  bubble,  for  a  French 
line,  being  one  minute  or  even  more.  The  plane  of  the  circu- 
lar level  is  that  horizontal  plane  containing  the  centre  of  the 
circle  engraved  on  the  glass  disc. 

The  Adjustment  of  the  Circular  Level  is  accomplished  as  fol- 
lows :  Place  it  upon  an  instrument  provided  with  leveling 
screws,  and,  by  means  of  the  latter  bring  the  bubbles  to  the 
centre  of  the  circle  engraved  on  the  glass.  Then  turn  the  level 
about  its  vertical  axis  and  note  in  what  position  it  attains  its 
maximum  deviation  of  bubble.  Correct  half  of  this  maximum 
deviation  by  means  of  the  proper  screws  attached  to  the  level, 
or,  if  there  are  no  screws,  by  a  proper  grinding  of  the  base. 
The  adjustment  may  be  verified  by  now  leveling  the  instru- 
ment and  again  testing  whether  the  bubble  remains  in  the 
centre  on  turning  the  level  about  its  vertical  axis.  The  prin- 
ciple involved  is  the  familiar  one  of  reversion,  fully  illustrated  in 
the  subsequent  explanation  of  the  use  of  the  cylindrical  level. 

The  usefulness  of  the  Circular  Level  arises  from  the  fact  that  it 
is  at  once  a  test  of  level  in  every  azimuthal  direction,  and 
therefore  requires  the  minimum  turning  of  the  instrument  to 
which  it  is  applied.  This  characteristic,  combined  with  its  low 
sensitiveness  ,  make  it  often  indispensable  for  the  economy  ot 
time.  It  is  attached  to  leveling  rods,  to  all  the  ordinary  sur- 
veying instruments,  and  even  to  the  finer  instruments  as  an 
important  accessory  conducive  to  rapidity  of  work. 


74 


THE    SPIRIT    LEVELS    OF 


THE  ADJUSTMENT  AND  USE  OF  A  STRIDING 
OR  OTHER  FINE  LEVEL. 

In  order  fully  to  explain  the  operations  and  precautions  nec- 
essary to  determine  the  inclination  of  a  line  by  means  of  the 
spirit  level,  or  to  render  a  line  horizontal,  we  will  describe  in 
detail  the  use  of  a  delicate  level  in  testing  the  inclination  to 
the  horizon  of  any  line,  as  for  example,  the  horizontal  axis 
of  a  theodolite.  Every  such  level,  and,  in  fact,  every  level 
capable  of  correct  use  possesses  at  least  two  means  of  adjust- 
ing the  direction  of  the  level  tube  with  respect  to  its  support, 
viz.,  First,  means  for  laterally  moving  one  end,  so  as  to  render 
the  level  parallel  to  the  line  intended  to  be  leveled.  The 
screws  for  accomplishing  this  are  called  "the  lateral  adjusting 


Fig.  40. 

screws."  Secondly,  it  possesses  means  for  vertically  mov- 
ing one  end  of  the  tube  with  respect  to  the  support,  so  as  to 
enable  the  bubble  to  be  brought  to  zero  when  the  line  of  the 
supports  is  horizontal.  This  line  of  the  supports,  of  an  ac- 
curately adjusted  level,  brought  in  physical  contact  with  any* 
other  line,  and  the  bubble  brought  to  zero,  the  other  line  is 
also  horizontal.  The  screws  used  for  accomplishing  the  vertical 
movement  are  called  "  the  vertical  adjusting  screws." 

Both  these  required  conditions  may  be  summed  up  in  the 
statement  that  the  axis  of  the  level  must  lie  in  the  same  plane 
as  the  line  whose  inclination  is  to  be  determined,  and  also 
parallel  to  the  physical  line  used  as  an  intermediary  for 
applying  the  level.  The  accompanying  Fig.  40  will  fully 


ENGINEERING    INSTKl'MKNTS.  75 

illustrate  the  mechanical  means  used  for  securing  these  adjust- 
ments. The  vertical  adjusting  screws  are  al>,  and  the  lateral 
adjusting  ones,  cd. 

The  cross-wise  position  of  the  level  with  respect  to  the  axis 
of  the  instrument  may,  in  the  case  of  this  striding  level,  be 
readily  tested.  Suppose,  for  example,  that  in  Fig.  40  the  end 
on  the  left  projects  forward,  and  the  end  on  the  right  to  the 
rear  of  the  instrumental  axis.  Rotating  the  level  on  the  in- 
strumental axis  toward  the  rear,  the  bubble  will  move  toward 
the  left,  because  that  end  is  thus  raised.  Moving  the  level 
forward,  the  bubble  will  be  displaced  toward  the  right.  If, 
however,  the  level  axis  is  parallel  to  the  instrumental  axis, 
there  will  be  no  movement  whatever  of  the  bubble  upon  rotat- 
ing the  striding  level  upon  the  instrumental  axis.  This  is  the 
first  adjustment  to  be  made.  It  should  also  be  tested  after 
the  second  adjustment. 

The  case  of  the  cross-wise  position  of  the  level  with  respect 
to  a  line  sight,  as  occurring  in  leveling  instruments,  is  also  of 
considerable  importance  and  is  fully  discussed  in  the  article  of 
this  Manual  entitled  "The  Adjustments  of  the  Engineer's 
Lev?/" 

The  parallel  position  of  the  level  axis  with  the  physical  line  or 
physical  plane  forming  the  base  of  the  level  can  be  secured  only 
after  making  a  complete  test,  as  now  to  be  explained.  The 
physical  plane  mentioned  is  here  the  plane  joining  the  points  of 
contact  of  the  inverted  V's  of  the  striding  level.  The  accurate 
use  of  a  level  always  requires  such  a  manipulation  as  shall 
eliminate  any  error  due  to  lack  of  parallelism  of  its  axis  with 
the  plane  forming  its  base.  It  is  not  always  necessary  nor 
even  desirable  that  the  error  shall  be  removed  by  adjustment, 
but  it  is  essential  that  its  value  be  known,  and  allowed  for. 
Moreover,  it  ought  to  be  distinctly  understood  that  there  is  no 
form  of  level  whatever  not  subject  to  this  error.  The  follow- 
ing method  of  observation  will  be  found  to  lead  both  to  the 
;lesired  accuracy  in  observation  and  to  the  neatest  means  of 
determining  the  error  and  of  accomplishing  this  adjustment  of 
the  level : 


76 


THE    SPIRIT    LEVELS    OF 


Let  AB  in  Fig.  41  represent  a  level  tube  applied  in  an  east- 


west  direction  to  a  truly 
horizontal  line  E.W. ;  e  and 
w  the  end  readings  of  the 
bubble.  Let  /  equal  the 
half-length  of  the  bubble. 
The  bubble  readings,  e  and 
w,  will  be  exactly  the  same, 
and  each  equal  to  /,  pro- 
vided,  First,  the  legs  AE 
and  BVV  are  equal  and, 
Secondly,  the  zero  point  0 
is  in  the  middle  of  AB.  If 
BW  is  the  longer  leg,  the 
bubble  will  stand  nearer  B 
by,  say,  y  divisions  ;  also, 
if  the  zero  0  stands  nearer 
A  by,  say,  z  divisions,  the 
reading  of  w  will  be  in- 
creased by  that  amount. 


Fig.  41. 


A 
E 

eO      w 

\ 

B 

W 

f^^^^^ 

eO 


W 


B 


W 


Fig.  42. 


Letting  e==y-\-s.     The  readings  for  the  ends  are  then : 

w  =  I  +  £ 
e=l—  £ 

But  if  the  end  B  be  now  raised,  as  shown  in  Fig.42,  through 
an  angle  a  which  would  of  itself  give,  say,  x  divisions  of  dis- 
placement, the  readings  in  this  position  of  the  level  will  then  be 


And,  if  we  now,  in  Fig.  42,  reverse  the  position  of  the  level, 
so  that  B  stands  over  E  and  A  over  W,  the  errors  j>-\-z=s, 
will  change  sign,  and  the  readings  of  the  bubble  ends  toward 
W  and  E  will  be  respectively, 


\ 


IV.2  —  /  -  £  -f-  X 


=          £ 


x 


(2) 


From  these  sets  of  equations,  j(i)  and  (2),  we  have 


ENGINEERING    INSTRUMENTS. 


77 


Hence      x  =  X  [  %  («'i  —  f  ,)  +  X  K  —  '2)] 

(W*   4-  If  2)  -  (^  4-  r2)  x    v 

or  finally  x=\-±  (4) 

4 

The  practical  rule  given  by  the  last  equation  is  :  Place  the 
level  on  the  given  inclined  line.  Read  the  divisions  at  the 
bubble-ends.  Reverse  and  read  again.  Add  together  the  two 
bubble-end  readings  of  the  one  end,  also  the  two  bubble-end 
readings  of  the  other  end,  and  divide  the  difference  of  these 
sums  by  four.  This  result  measures,  in  divisions  of  the  level, 
the  elevation  of  the  end  with  the  greater  sum  of  readings. 

In  order  to  find  the  angular  elevation  we  must  multiply  the 
number  of  divisions,  ;/,  of  bubble  displacement,  by  the  value  of 
a  division  in  arc,  d,  to  obtain  the  angle  a,  or,  a  =  nd. 

The  errors  y  and  2  cannot  be  found  separately,  but  their 
sum,  e,  is  readily  found  from  equations  (3). 


If  the  level  always  remained  in  a  constant  condition,  the 
errors  y  and  z  could  be  found  and  corrected,  and  their  sum 
being  then  zero,  either  of  the  equations,  (3),  would  give  x 
without  reversal  of  the  level.  In  refined  leveling  this  con- 
stancy should  never  be  assumed.  It  is,  however,  always 
convenient  to  render  £  as  nearly  as  possible  equal  to  zero. 

A  practical  example  is  furnished  by  the  following  readings 
of  a  level  placed  on  the  horizontal  axis  of  an  instrument  : 


W. 

E. 

w  —  e 

First  position, 

24.1 

26.3 

2.2  = 

Second  position, 

29.2 

21.2 

+  8.0  = 

Sums, 

53.3 

47-5 

4)  —  10.2 

47-5 

—  2.55  = 

4)5-8 

1.45= 

X 

78  THE    SPIRIT    LEVELS    OF 

Assuming  the  value  of  a  division,  d,  of  this  level  as  1.8", 
the  west  end  of  the  axis  of  the  instrument  inclines  upward 
by  1.45  times  this  amount,  or  2.6". 

The  negative  sign  of  s  shows  that  in  the  first  position  of  the 
level,  the  west  end  bubble  reading  is  too  small,  or  the  west  end 
of  the  tube  is  too  low  by  that  amount.  The  vertical  adjusting 
screws  must  therefore  be  so  turned  that  for  this  position  the 
bubble  is  brought  west  2.55  divisions.  This  being  done,  the 
reading  for  each  position  of  the  level,  direct  and  reversed,  will 
be  26.65  and  23.75  for  the  west  and  east  end  respectively; 
and  in  either  position  of  the  level,  one-half  the  difference  of  the 
bubble-end  readings  will  give  the  number,  1.45,  of  bubble-divi- 
sions of  inclination  of  the  axis  of  the  instrument. 

Change  of  bubble  length  due  to  change  of  temperature  dur- 
ing the  reading  of  the  level  may  introduce  an  error.  It  is 
eliminated  by  arranging  the  several  readings  in  the  two  posi- 
tions of  the  level  symmetrically  with  respect  to  the  time.  For 
reasons  to  be  stated  under  the  head  of  errors  of  the  level,  each 
set  of  readings  should  be  made  an  independent  one  by  lifting 
the  level  after  each  observation  of  both  ends  of  the  bubble. 
The  rule  would  then  be :  Read  the  bubble-ends  once  in  the 
first  position  of  level,  twice  in  the  second  position  (taking  care  to 
lift  level  between  these  observations),  and  once  again  in  the  first 
position.  The  difference  of  the  sums  of  readings  on  the  same 
side,  divided  by  the  whole  number  of  end  readings,  is,  in  bubble- 

j  o     * 

divisions,  the  inclination  upward  of  the  side  having  the  greater 
sum  of  readings. 

METHODS  OF  FINDING  THE  VALUE  OF 
A  DIVISION  OF  A  SPIRIT  LEVEL. 

Taking  great  care  to  place  the  level  tube  while  it  is  being 
tested  under  precisely  the  same  conditions  as  when  it  is  in 
use  in  connection  with  the  instrument,  a  spirit  level  may  have 
the  value  of  a  division  determined  by  one  or  other  of  the  fol- 
lowing methods : 

i.  By  the  use  of  a  Vertical  Circle.— If  a  finely  divided  verti- 


i-:.\( . i  NKKRI N< ; 


79 


cal  circle  is  at  hand,  the  value  of  a  division  may  be  deter- 
mined by  suitably  attaching  the  level  in  the  plane  of  the  circle 
and  simultaneously  taking  the  readings  of  the  circle  and  of  the 
level  with  the  bubble  near  one  end,  and  then  by  a  slight  rotation 
bringing  the  bubble  near  the  other  end  and  taking  the  simul- 
taneous readings.  The  value  of  one  division  of  the  level  will 
evidently  result  from  a  division  of  the  number  of  seconds  of 
an  j^le  measured  on  the  circle,  by  the  number  of  divisions  of 
bubble  displacement.  By  taking  simultaneous  readings  with 
bubble  in  various  positions  of  the  tube,  the  equality  of  value 
of  the  divisions  of  the  level  may  be  tested. 

2.  By  Means  of  Instrument  and  Rod.  —  A  convenient,  practical 
method  of  finding  the  value  of  a  division  of  the  level  of  an 
engineer's  transit,  or  of  an  engineer's  level,  consists  in  sighting 
the  telescope  to  a  leveling-rod  set  at  a  known  distance  from 
the  instrument,  and  causing  the  bubble  to  run  first  toward  the 
eye-end  and  then  toward  the  object-end  of  the  level  tube,  at 
the  same  time  that  the  rod  readings  are  taken  for  these  different 
positions  of  the  bubble.  If  D  represents  the  distance  of  the 
rod  from  the  instrument;  r,  the  difference  of  the  rod-readings 
for  the  two  positions  of  the  bubble;  ?/,  the  number  of  divisions 
traversed  by  the  centre  of  the  bubble;  dr^  the  value  of  one 
division  of  the  level  in  units  of  the  rod  for  the  unit  distance, 
and  ds  the  value  of  one  division  of  the  level  in  seconds  of  arc, 
we  have 


and  d*  =  206  265  -/"   ,  (2). 


If  we  let  Ee  equal  the  eye-end  reading,  and  Oe  the  object- 
end  reading  of  bubble  for  the  bubble  run  toward  the  eye-end 
of  the  tube  ;  E0  the  eye-end  reading,  and  00  the  object-end 
reading  of  the  bubble  for  bubble-run  toward  object-end  of  the 
tube  ;  Re  the  red  reading  for  bubble  run  toward  eye-end, 
and  R0  the  rod  reading  for  bubble-run  toward  object-end,  the 
bubble  deviation  being  counted  from  the  middle  of  the  tube, 
and  reckoned  positive  if  toward  the  object-end,  we  may  write 
equations  (i)  and  (2)  in  the  following  suggestive  forms  : 


8o 


THE    SPIRIT    LEVELS    OF 


R.  —  R, 


D 


£"  L-n     \ 


And 


(R0  —  Re )  206  265 
Oe—Ee 


D 


(3) 


(4) 


It  is  advantageous  in  practice  to  let  each  one  of  the  let- 
ters representing  readings  in  equations  (3)  and  (4)  stand 
for  the  mean  of  a  number  of  readings.  Equation  (3) 
will  be  found  useful  in  computing  a  table  of  corrections 
to  the  rod-readings,  corresponding  to  various  distances  and 
bubble  deviations,  incident  to  the  use  of  an  Engineers'  Transit 
or  Engineers'  Level. 

3.  By  Means  of  a  Level-Trier. — The  level-trier  is  an  instru- 
ment specially  designed  for  determining  the  value  of  a 
division  of  a  level  and  investigating  the  uniformity  of  that 


Fig.  42. 

value  in  different  parts  of  its  scale;  and  under  different  con- 
ditions of  temperature.  Figure  42  gives  a  perspective  view 
of  a  level-trier,  or  level-tester.  This  instrument  consists  of  a 
main  T-formed  plate  A  mounted  on  three  leveling-screw*; 
a  second  plate  B  hinged  to  the  former  at  one  end,  by  means 
of  accurate  pivots,  and  hence  capable  of  having  the  height  of 
the  other  end  varied  by  means  of  a  fine  micrometer  screw 
5  placed  there.  This  screw  is  provided  with  a  graduated 
head,  from  which  the  seconds  of  arc  may  be  directly  read  off 
Slides  with  suitable  V's  rest  upon  the  movable  plate,  and 
serve  to  hold  in  place  levels  of  various  lengths. 


ENGINEERING    INSTRUMENTS.  8l 

The  theory  of  the  level-trier  is  very  simple.  If  the  length, 
( X  accurately  measured  from  the  centre  of  the  axis  C  to  the 
axis  of  the  micrometer  screw,  6",  be  designated  by  /,  one  thread 
interval  of  the  micrometer  by  /*,  the  total  number  of  divisions 
on  the  graduated  micrometer-head,  Ar,  and  ;/  the  number  of 
these  corresponding  to  /divisions  of  the  level,  then  the  angular 
value,  */,  of  one  division  of  the  level  will  be  given  by  the 
equation 

,  _    fi     n  206  26 j 
/.     A"        / 

Here  .'.-  is  evidently  the  tangent  of  the  angle  corresponding 
to  a  single  turn  of  the  micrometer  screw,  and  since  this  angle 
is  small,  Jj-  jo6  265  represents  the  value  of  the  angle  itself. 

The  relations  of  «,  /,  and  N  are  so  taken  as  to  enable  the 
micrometer-head  to  be  read  directly  to  seconds. 

THE  FAULTS  OF  LEVELS. 

The  faults  to  which  levels  are  subject  are  the  more  worthy 
of  remark,  because  so  frequently  overlooked,  even  by  expert 
observers.  Moreover,  it  sometimes  happens  that  a  whole 
series  of  very  important  measures  is  cast  into  doubt  or  alto- 
gether lost  by  a  level  which,  from  original  faulty  construction, 
suddenly  shows  seemingly  inexplicable  errors. 

Irregularities  in  the  curve  to  which  the  level  is  intended  to 
be  ground,  will,  of  course,  produce  irregular  values  for  the 
different  divisions.  These  values  may,  indeed,  be  investigated, 
and  a  table  of  them  used  for  the  various  deviations  of  bubble ; 
but,  practically,  it  is  found  best  to  reject  all  such  levels  or 
re-work  their  curves. 

Improper  length  of  bubble  may  be  due  to  original  fault  in 
filling,  to  leakage,  to  variations  in  the  diameter  of  the  level- 
tube,  or  finally  to  excessive  temperature  changes.  Low  tem- 
perature lengthens  and  a  high  temperature  shortens  the 
bubble.  It  is  found  that  extreme  shortness  or  length  of  the 
bubble  somewhat  influences  the  value  of  a  division  of  bubble- 


82  THE   SPIRIT    LEVELS    OF 

displacement.  The  bubble  should  not  much  vary  from  one- 
fourth  to  one-half  the  whole  length  of  the  tube.  A  length  of 
one-third  that  of  the  tube  is  a  good  average. 

Temperature  variations  not  only  affect  the  length  of  bubble, 
but  may  cause  unequal  stresses  on  the  tube,  owing  to  improper 
methods  of  securing  it  in  its  case.  Particularly  is  unequal 
heating  of  the  level  to  be  carefully  guarded  against.  The 
bubble  always  moves  toward  the  point  of  higher  temperature, 
and  hence  unequal  temperature  of  tube  may  entirely  destroy 
its  value  as  a  level.  Levels  should  therefore  be  guarded  from 
the  direct  rays  of  the  sun,  and  from  bodily  heat. 

Particles  of  dust  and  glass  in  the  sealed  tube  have  been  found 
to  produce  very  serious  and  often  mysterious  errors  in  the  in- 
dications of  levels.  Astronomers  and  others  called  upon  to 
do  delicate  work  with  levels,  have  frequently  verified  the 
curious  behavior  of  levels  without  quite  comprehending  the 
nature  of  the  defect.  QUEEN  &  Co.  employ  a  kind  of  glass 
and  a  method  of  preparing  the  tubes,  and  of  filling  them, 
which  effectively  obviate  this  serious  and  unexpected  class  of 
errors. 

The  elimination  of  errors,  like  those  just  mentioned,  may 
perhaps  best  be  accomplished  by  frequent  disturbances  and  re- 
readings  of  the  bubble  during  the  progress  of  any  work  of 
special  importance.  Any  tendency  toward  constancy  of  error 
may  thus  be  translated  into  the  province  of  accidental  and 
.compensating  errors.  A  level  containing  free  solid  particles 
or  crystals  formed  by  deterioration  of  the  glass  is,  however, 
prone  to  systemattc  error  under  all  conditions  of  use. 

The  deterioration  of  levels,  although  much  discussed  in  tkc 
past,  has  only  recently  received  a  scientific  explanation,  and  an 
adequate  remedy  through  the  elegant  investigations  of  Prcfjs- 
sor  R.  Weber,  of  Berlin.  This  noted  chemist  has  put  it  beyond 
question  that  the  ordinary  soft  qualities  of  glass  are  dissc.Ved 
by  water  admitted  with  the  ether,  and  that  the  quant--;  /  of 
crystalline  matter  developed  inside  of  level  tubes  is  propof 
both  to  the  impurity  of  the  ether  and  the  solubility  of  the 


ENGINEER  I  Xi ;    INSTRUMENTS.  83 

This  he  has  verified  chemically  In. several  scientifically  selected 
test  cases,  as  well  as  by  reference  to  some  fifty  different  levels. 

The  high  importance  of  his  investigations  lies  not  only  in 
having  disclosed  the  true  causes  of  the  deterioration  of  levels 
but  in  having  proposed  and  thoroughly  tested  a  form  of  level 
whose  permanence  max*  be  guaranteed. 

Two  points  have  to  be  attended  to  in  making  durable  levels. 
First,  the  glass  must  be  of  a  special  chemical  constitution,  and 
secondly,  the  ether  used  for  filling  must  be  freshly  rectified  and 
freed  from  every  trace  of  water.  Deterioration  is  certain  to 
follow  the  omission  of  either  precaution.  Levels  filled  for  a 
long  while  should  hence  always  be  carefully  examined  for  the 
characteristic  clouding  of  the  interior  before  being  too  confi- 
dently trusted  in  any  delicate  work.  QUEEN  &  Co.  now  un- 
dertake to  furnish  fine  levels  with  the  special  glass  and  filling. 

NEW  FORMS  OF  LEVELS. 

Mr.  H.  H.  Turner,  of  the  Greenwich  Observatory,  suggests 
a  form  of  level  which  is  practically  a  combination  of  level 
and  level-trier  in  one  instrument.  This  is  accomplished  by  the 
addition  of  a  micrometer  screw  and  system  of  levers  for  deli- 
cately moving  the  bubble  and  bringing  it  to  the  same  mark  in 
each  position  of  the  level.  Inequalities  of  the  scale  do  not 
affect  the  readings  in  this  form. 

Dr.  A.  A.  Common,  of  the  Royal  Astronomical  Society, 
goes  a  step  further  and  proposes,  in  refined  work,  to  discard 
the  filled  level  altogether,  and  in  its  place  substitute  a  horizon- 
tal telescopic  line  of  sight,  whose  direction,  beyond  the  object- 
glass  of  the  device,  is  rendered  vertical  by  means  of  a  right- 
angled  prism,  and  then  verified  by  reflexion'  from  mercury  ac- 
cording to  the  familiar  Bohnenberger  method. 

THE  LEVELS  AS  APPLIED  TO  INSTRUMENTS/ 

The  Engineer's  Transit  of  the  ordinary  form  usually  has  three 
levels,  two  applied  to  the  alidade  and  one  of  considerable  sen- 
sitiveness attached  to  the  telescope  and  enabling  the  instru- 
ment to be  .used  for  leveling.  If  the  instrument  be  designed 


84       THE    SPIRIT    LEVELS    OF    ENGINEERING    INSTRUMENTS. 

to  measure  vertical  angles  with  accuracy,  it  may  have  a 
level  attached  to  the  vernier  arm  of  the  vertical  circle.  If  de- 
signed for  straight  line  work  or  for  geodetic  use,  it  may  have 
a  sensitive  striding  level.  The  solar  attachment  as  applied  to 
the  transit  also  requires  a  small  level  to  set  the  solar  telescope 
to  the  required  inclination.  Instead  of  two  cylindrical  levels, 
one  circular  may  be  applied  to  the  alidade. 

The  axis  of  each  plate-level  is  adjusted  so  as  to  be  at  right 
angles  to  the  vertical  axis  of  the  instrument.  The  axis  of  the 

^5 

telescope  level  is  adjusted  parallel  to  the  line  of  sight  o*f  the 
telescope.  The  bubble  of  the  level  of  the  vertical  circle  is  ad- 
justed to  read  zero  when  the  line  of  sight  is  horizontal  and  the 
vernier  of  the  vertical  circle  reads  zero.  The  axis  of  the  strid- 
ing level  is  intended  to  be  at  right  angles  to  the  vertical  axis 
of  instrument,  and  its  adjustment  and  use  have  already  been 
fully  explained.  The  axis  of  the  level  attached  to  the  solar 
telescope  is  adjusted  to  be  parallel  to  the  line  of  sight  of  that 
telescope,  when  this  line  is  parallel  to  the  sight-axis  of  the 
main  telescope. 

The  Engineer's  Level  has  ordinarily  but  one  level  attached 
parallel  to  the  telescope.  Sometimes,  however,  it  is  considered 
advantageous  to  have  small  cylindrical  levels  or  a  circular  level 
attached  to  the  leveling  head  of  the  instrument  for  use  in  rough 
adjustment  of  the  instrument.  The  axis  of  the  telescope  level 
is,  by  adjustment,  brought  parallel  to  the  sight-axis  of  the  tele- 
scope, and  must  be  of  a  sensitiveness  proportional  to  the 
accuracy  of  which  the  instrument  as  a  whole  is  to  be  capable. 

Other  instruments,  like  the  Engineer's  Compass,  and  the 
Plane  Table,  as  well  as  the  usual  Geodetic,  and  Astronomical 
instruments,  have  levels  for  similar  purposes  which  will  be 
readily  understood  from  the  discussions  of  this  article. 

Queen  &  Co.  take  no  little  pains  to  make  the  levels  of  their 
instruments  of  reliable  construction  and  of  a  sensitiveness 
suited  to  the  purpose  of  the  particular  level  and  instrument. 
They  also  specially  aim  to  so  graduate  all  the  levels  as  to  facili- 
tate their  convenient  reading  and  proper  use.  The  value,  in 
angular  measure,  of  a  division  of  each  level  is  furnished  by 
th^ii  in  the  certificate  accompanying  each  instrument. 


QUEEN"  BUILDERS'  TRANSIT. 


A  1521. 


THE  TELESCOPES 

OF 

ENGINEERING   INSTRUMENTS. 


A  GOOD  telescope  is  generally  admitted  to  be  an  essen- 
tial feature  of  an  engineer's  transit  or  of  an  engineer's 
level,  and  yet  it  is  very  doubtful  whether  the  points 
necessary  to  excellence  in  the  optical  parts  of  the  instrument 
are  always  fairly  understood,  since  even  direct  misstatements 
of  the  scientific  facts,  such  as  that  the  excellence  of  a  tele- 
scope is  determined  by  its  high  magnifying  power,  are  used 
as  a  means  for  exploiting  inferior   instruments.     A  detailed 
discussion  of  the  construction  of  the  telescope  will  best  show 
in  what  points  excellence  consists. 

Every  telescope  consists  of  three  essential  parts :  First,  the 
image-forming  apparatus  ;  second,  the  image-examining  ap- 
paratus ;  and  third,  the  tube.  If  the  telescope  is  to  be  used  for 
measuring  purposes  a  fourth  essential  is  a  set  of  cross  wires  in 
the  common  focus  of  the  objective  and  eye-piece.  In  refract- 
ing telescopes,  such  as  exclusively  used  in  engineering  instru- 
ments, the  image  is  formed  by  an  object-glass  or  objective 
through  which  the  light  is  transmitted.  By  means  of  the  object- 
glass,  the  rays  are  so  bent  as  to  unite  in  a  certain  plane  behind 
the  lens,  called  the  focus,  and  there  form  a  small  image  or 
picture  of  the  objects  toward  which  the  telescope  is  directed. 
This  imago,  which  may  be  readily  seen  by  the  unaided  eye  by 
placing  a  dull  white  surface  in  the  focal  plane,  is  then  exam- 
ined by  a  set  of  lenses  called  the  eye-piece  or  ocular,  which 
acts  like  an  ordinary  hand  magnifier  or  single  short-focus  lens, 
and  causes  the  image  to  appear  enlarged  and  clearly  visible 
to  the  examining  eye.  The  tube  holds  the  object-glass  and 
eye-piece  in  proper  relation  to  one  another. 

The  Simple  Astronomical  Telescope  of  Kepler,  Fig.  10,  con- 

85 


86 


THE    TELESCOPES    OF  'ENGINEERING    INSTRUMENTS. 


sisting  of  two  simple  convex  lenses,  one  of  long  focus,  0,  the 
objective,  and.the  other  of  short  focus,  E,  the  ocular,  is  the  best 
form  to  consider  in  a  discussion  of-the<  general  properties  of  the 
telescope.  In  the  Kepler  "teles cope  the' 'distance  apart  of  the 
two  lenses  when  a  distant  object  is  viewed  is  equal  to  the  sum 
of  the  focal  lengths  of  the  Senses.  T-he'Compoimd/arhromatic 
objectives 'and  oculars  of  other  telescopes  may  be  regarded  as 
single  lenses  whose  equivarenribcal  lengths  and  positions  are 
such  as  to  produce  a  similar  optical  result. 


.  Fig.  10. 

The  magnifying  power  of  any  telescope  is  equal  to  the  ratio 
of  the  angular  size  of  the-  object'  ;as  it  appears  in  the  telescope 
to  that  which  it  presents  to'  the  naked  eye,  -or,  in  Fig.  10,  the 
ratio  of  Mg=MENto  bOa±=.MO  N,  which,  since  .the  angles 
are  small,  is  equal  to  the  ratio  of  Oi,  the  focal  length,  F,  of 
the  objective  to  Ei,  the  focal  length,/,  of;  the  eye-4ens.  If  M 
designates  the  magnifying  power, 


It  being  difficult  and  inconvenient  to  measure  the  focal  lengths 
of  the  lenses  with  accuracy,  the  magnifying  power  is  practi- 
cally measured  by  other  methods  presently  to  be  mentioned*. 

The  Field  of  View  is  the  angular  space  that  can  be  viewed 
with  the  telescope  at  one  and  the  same  time.  The  angle 
formed,  Fig.  10,  .by  the  two  .principal  rays,  a  and  b,  passing 
through  the  centre,  .0,  of  the  objective  and  tangent  to  the 
diaphragm  of  the  ocular,  or  the  angle  aQb=gOh,  measures 
•the  field  of  view.  The  effective  aperture  of  the  ocular  thus 
alone  Determines  the  size  of  the  field. 


THE    TELESCOPES    <>l      KNt  ,  I  XEEK  1  N<  ,     IXSTKOfEXTS  87 

The  field  decreases  with  the  increase  of  magnifying  power. 
If  we  let  a  equal  the  aperture  of.the  eye-lens,  J/the  magnify- 
ing  .power  of  telescope,  /•  the  focal  length  of  objective,  and/ 
focal  length  of  eye-lens,  then  in  minutes  of  arc, 


;  as  isruspal,  a  ==  *^/,-  the*  following  relations  result  ; 


Mag.  power,  \io        20     30    40     100      ... 
.  Field,  *°  39'   i  °  26'  56'    43':!;' 

.  }     '.          '   •  ,      i      '          .  .     • 

The  brightness  of  objects  as  seen  through  the  telescope  de- 
pends upon  (l).the  proportion  of  the  Jight,  L,  transmitted 
through  the  lenses  ;,  (2)  the  clear  aperture.  of  the  objective,  A  ; 

-  »  ,  /  *      • 

(3)  the  aperture  ofthe  pupil  of  the  observer's  eye,  e  •;  and  (4) 
the  magnifying  power,  M.  The  proportion  of  light  trans- 
mitted through  the  best  achromatic  telescopes,  taking  the 
brightness  as  seen  with^the  unaided  eye  as  I,  is  eighty-five  per 
cent.,  though  this  proportion  may  in  inferior  instruments  de- 
scend to  seventy  per  cent.  If  B  represents  this  brightness, 
the  expression  for  it  will  'be  : 


13 


which  indicates  that  the  brightness  of  objects  as  seen  through 
the  telescope  increases  in  proportion  to  the  square  of  the  in- 
strument's aperture  and  decreases  as  the  square  of  its  magni- 
fying power.  It  is  thus  seen  that  increase  of  magnifying  power 
very  rapidly  decreases  brightness.  A  limit  of  decrease  of 
brightness  beyond  one-half  that  presented  to  the  unaided  eye 
should  never  be  allowed. 

The  maximum  brightness  of  objects  giving  a  sensible  size 
of  image  is  attained  when  the  diameter  of  the  cylinder  of  rays 
issuing  from  the  telescope  equals  the  aperture  ofthe  eye.  The 
brightness  is  then  equal  to  the  natural  one.  Stars  being, 
under  all  telescopic  powers,  mere  points,  increase  in  brightness 


88  THE    TELESCOPES    OF    ENGINEERING    INSTRUMENTS. 

beyond  the  natural   brightness  in  the  ratio  of  the  squares  of 
the  apertures  of  the  objective  and  of  the  eye. 

The  Simple  Objective,  formed  of  a  single  lens,  has  two 
serious  defects.  First,  the  image  is  fringed  and  rendered  in- 
distinct by  the  spectral  colors,  and,  secondly,  the  image  is  so 
curved  that  when  projected  on  a  plane  it  appears  for  the  most 
part  indistinct  and  hazy. 

The  Achromatic  Objective,  formed  by  combining  two  lenses 
•of  different  dispersive  and  refractive  powers,  usually  of  crown 
.and  flint  glass  respectively,  may  be  so  constructed  as  almost 
wholly  to  avoid  these  two  defects  of  chromatic  and  spherical 
aberration.  The  achromatism  or  colorlessness  of  the  image 
will  then  depend  on  the  ratio  of  the  focal  lengths  of  the  two 
lenses,  while  the  freedom  from  spherical  aberration  or  from  a 
nebulous,  milky  appearance  of  the  image  will  be  determined 
by  the  ratio  of  the  curvatures  of  the  lenses. 

The  eye-pieces  of  a  telescope  may  be  of  two  kinds,  astronomi- 
cal and  terrestrial,  the  former  usually  comprising  two  lenses, 
and  showing  the  image  in  the  same  inverted  condition  in 
which  it  is  formed  by  the  objective,  and  the  latter  usually  com- 
prising four  lenses  and  erecting  the  image.  Although  the 
terrestrial  eye-piece  is  inferior  in  point  of  optical  performance, 
it  is  still  generally  preferred  by  American  engineers. 

The  Astronomical  Eye-pieces  are  either  of  the  Huyghenian  or  of 
the  Ramsden  form.  The  former,  or  negative  eye-piece,  is  used 
only  for  its  qualities  as  a  good  seeing  ocular,  but  cannot  so 
well  be  used  with  cross- hairs,  both  because  the  focus  lies  be- 
tween the  lenses  and  because  the  hairs  can  only  be  well  de* 
fined  in  the  centre  of  the  field.  It  consists  of  two  plano- 
convex lenses,  with  their  convexities  turned  toward  the  object- 
glass. 

The  Ramsden,  or  positive,  consists  of  two  plano-convex 
lenses,  with  their  convexities,  turned  toward  each  other.  The 
focus  of  this  ocular  lies  in  front  of  the  field-lens,  and  it  is 
for  this  reason,  as  well  as  on  account  of  defining  the  threads 
well  over  the  whole  field,  adopted  for  use  with  micrometer 


THK     N-:i.i>0»I'ES    OF    EXV.IXEKRIXr;    TXSTRl'MKXTS.  89 

threads.     The  purely  optical  defects  of  the  positive  for  seeing 
purposes  are  greater  than  those  of  the  negative  eye-piece. 

The  terrestrial  eye-pieces  are  usually  composed  of  four 
lenses,  the  first  two,  counting  from  the  objective,  being  called 
the  erectors.  The  focus  of  this  lens,  as  shown  in  Fig.  u,  lies 
in  front  of  the  first  lens,  and  it  is  at  that  point'  that  the  cross- 
hairs are  placed.  The  theory  of  this  eye-piece  is  too  compli- 


cated to  be  entered  into  here.  Suffice  it  to  say  that,  on 
account  of  the  number  of  possible  variables,  the  production 
of  an  excellent  eye-piece  involves  science  and  art  in  combina- 
tion that  is  the  exclusive  property  of  the  expert  optician.  The 
various  forms  known  as  the  Fraunhofer,  Kellner,  Airy,  Stein- 
heil,  etc.,  are  to  be  selected  by  the  skilled  optician  with  regard 
to  the  particular  service  to  which  the  telescope  is  to  be  put. 

The  clear  aperture  of  a  telescope  is  determined  by  the  size 
of  the  pencil  of  light  which  passes  through  the  entire  instru- 
ment. The  pencil  entering  the  object-glass  may  be  partly  cut 
off  by  diaphragms,  and  thus  the  apparent  aperture  may  not  be 
the  real  one.  Inferior  telescopes  not  infrequently  have  a  con- 
siderably less  clear  aperture  than  apparent.  The  following 
method  is  an  easy  test  of  the  true  aperture :  First,  having 
focused  the  telescope  for  distant  objects,  direct  it  to  a  bright 
cloud,  or  the  well  illumined  sky,  and  bring  the  eye'  to  a  posi- 
tion behind  the  eye-hole  and  at  a  distance  from  it  equal  to 
that  of  distinct  vision,  so  as  to  permit  the  well-defined  little 
"  Ramsden's  Circle,"  or  image  of  the  objective  formed  by  the 
eye-piece,  to  be  clearly  seen.  Then  take  a  sharp  pencil 
point  and,  placing  it  at  the  edge  of  the  object-glass,  move 
it  across  toward  the  centre  and  note  the  point  where  it 
first  becomes  visible  in  the  little  Ramsden  disc.  Subtract 


9^  THE    TELESCOPES    OF    ENGIXEERING  "I^7STRtfMENTS. 

double-  this  distance  of  tHe  pencil  point  from  tHe  edge  from 
the  entire  diameter  of  the  object-glass,  and  the  result  is  the 
clear  aperture.  A -.magnifier  or  low  power  microscope  may 
be  used  for  observing  the  little  Ramsden  circle  and  the  ap- 
pearance of  the  pencil  point  in  it. 

Diaphragms  properly  placed  in  the  main  tube  are  necessary 
for  'the  exclusion  of  scattere'cfand  injurious'  fays.  But  through 
ignorance  of  the .  optical  theory  determining  their  use,  they 
are  often  so  inserted  as  to  vitiate  this'purpose,  and  also  reduce 
the  effective  aperture  and  the  field  of  view. 

The  eye-hole  is  such  a  diaphragm,  and  is  intended  to  be  so 
placed  that  the  eye  can  easily  be  brought  to  that  position  be- 
hind the  eye-piece  where  the1  entire  cone  of  rays  may  enter 
the  eye.  Its-,size  arid^position  can, -as  in  the  case  of  the  other 
diaphragms,  be  computed  only  from  the  course  of  two  princi- 
pal rays,  through  the.  system  of  lenses. 

The  line  of  sight  of  a  -telescope,  if  determined  by  two  fixed 
points,  namely,  (i)  the  optical  centre  of  the  objective 'and  (2) 
the  centre  of  the  cross-wires.  The  Image  of  a  point  of  an 
object  is  brought  centrally  upon  the  crossing-point  'of  the 
threads,  and,  since  the  rays  of  each  point  of  the  object  must 
have  passed  through  the  optical  centre  of  the  objective,  these 
two  points — "  optical  centre  "  and  "  crossing-point  of  the 
threads  " — fix  the  direction  of  the  "  line  of  sight,"  or  "  sight 
axis,"  or  "  sight  line."  If  we  speak  according  to  the  modern 
Gaussian  theory  of  lenses,  the  first  point  is  known  as  "  the 
second  principal. point  "  of  the  objective.  •  It  is  also  .seen  that 
since  this  "  second  principal,  point  "  is,  for  the  objective  and 
telescope,  a  fixed  point,  all  adjustments  of  the  line  of  sight  * 
are  made  by  moving  the  cross-hair  ring,  and,  moreover,  that 
any  point  on  any  thread  may  be  selected  as  the  second  point 
determining  the  line  of  sight,  but  that  for,  convenience  and 
definiteness  the  crossing-point  of  the  two-  middle  threads  is 
used. 

The  line  of  collimation  of  a  telescope  is,  strictly  speaking, 
the  mathematical  line  at  right  angles  to  a  certain  axis.  In  the 


THK    ri:i.i>o»n:-' fi-  K-M,INHKKL\<,    INSTKTMENTS.         91 

Engineers'  Transit,  and  all  o£her"instrumeritS  of  that  class,  the 
line  of  collimation  is  the  line  at  right  angles  to  the  horizontal 
axis  of  the  telescope*  'An  instrument  is  said  to  be  collimated 
when  the  line  of  sight,  is  .brought' into  coincidence  with  the 
line  of  collimation,  or  in.  the  -transit  when  the-line  of  sight  is  at 
right  angles  to  the  horizontal  axis.  '/The  term,  •'  line  of  colli- 
mation," is  often  erroneously t and-  loosely  used  by  writers  for 
"  line  of  sight."  ;  '  .  -  .  ; 

The  centering  of  the  telescope  involves  a  number  of  delicate 
operations  and  adjustments  implied  in  trie'  processes  (i)  of 
centering  each  lens  ;  (2)  of  centering  each  combination  of 
lenses — (a)  objective,  (&)  eye:piece;  (3),  of  centering  these 
combinations  with  respect  to  the  tube  ;  and  (4)  "of  centering 
the  cross-hairs  with  respect  to  the  optical  and  mechanical  axis. 

-  '  The  centering  of  a  lens  must  be  performed  in  the  grinding 
process.  .A  lens  is  truly  centered  when  the'  centre.,  of  the 
eitcle  determining  its  size  lies,  in  the  line  joining  the  thickest 
or  the  thinnest  part — that  is,  in  the  axis — of  the  lens.  . 

'       •      ~  |  -        ;       * 

The  centering  of  the  objective  in  its  cell  involves  not  only  the 
primary  centering  of  each  of  the  two  lenses,  but  their  careful 
relative  adjustment,  so  as  to  make  the  axis  of  each  lie  accu- 
rately in  the  same  straight  line.  This  common  axis  of  the  ob- 
jective lenses  is  thenceforth  regarded  as  the  optical  axis  of  the 
telescope  to  which1  all  else  must  be  centered.  So  important 
and  delicate  is  this  centering  of  -the  objective  in  its  cell  that 
ho  one  except  the  skilled  6ptician  shbuld  attempt  to  disturb 
it  by  removal  of  the  lenses.  The  centering  of  the  ob- 
jective may  be  tested  by  setting  the  cross-hairs  upon  some 
point,  and  noting  whether,  upon  unscrewing  the  objective 
through  a  complete  turn,  the  point  remains  bisected.  All 
telescopes  have  this  error,  ajt  least  to  some  small  extent,  and 
the  object-glass  should  therefore  be  screwed  in  securely,  and 
always  remain  in  the  same  position.  This  proper  position  is 
always  marked  in  QUEEN  &  Co.'s  instruments. 

The  centering  of  the  lenses  in  the  ocular  tube  is  necessary  to 
the  proper  optical  performance  of  the  eye-piece,  and  once  ac- 


92  THE    TELESCOPES    OF    ENGINEERING    INSTRUMENTS. 

complished  by  the  maker,  is  not  to  be  disturbed  by  unskilled 
hands. 

The  centering  of  the  objective  slide  is  readily  tested  in  the 
telescope  applied  to  leveling  instruments.  For  after  having 
centered  the  cross-hairs,  with  the  telescope  focused  for  very 
distant  objects,  the  slide  is  tested  by  focusing  on  a  very  near 
object,  and  noting  whether,  upon  rotating  the  telescope  about 
its  mechanical  axis,  a  point  remains  bisected.  If  there  is  a 
deviation,  one-half  its  apparent  value  must  be  corrected  by 
means  of  the  slide-centering  screws. 

In  the  telescope  of  the  Engineers'  Transit  the  following 
method  is  used :  Sight  to  a  distant  point,  note  it,  and,  clamp- 
ing the  horizontal  circle,  focus  upon  a  near  point.  Now  turn 
the  instrument  half-way  round  horizontally  and  transiting  the 
telescope  sight  to  the  near  point.  Clamp  horizontal  circle 
and  focus  for  the  distant  point.  If  the  cross-hairs  accurately 
bisect,  it  there  is  no  error  of  the  slide.  Otherwise,  one-half 
the  apparent  error  is  to  be  corrected  by  means  of  the  slide- 
centering  screws. 

This  centering  is  important  where  both  long  and  short 
sights  enter  into  the  work.  Any  error  due  to  it  is,  of  course, 
eliminated  by  keeping  the  focus  and  distances  constant. 

The  centering  of  the  cross-hairs,  assuming  that  the  objective 
is  correctly  centered,  may,  in  cases  where  the  telescope  can  be 
rotated  about  its  mechanical  axis,  as  in  the  Engineers'  Level, 
be  accomplished  as  follows :  Sight  to  a  distant  point,  and 
note,  upon  rotating  the  telescope  180°  in  its  wyes,  whether 
the  point  remains  bisected.  One-half  the  apparent  deviation 
is  to  be  corrected  by  means  of  the  cross-hair  screws.  In  tele- 
scopes of  the  Engineers'  Transit  this  centering  is  practically 
involved  in  bringing  the  line  of  sight  into  coincidence  with  the 
line  of  collimation  as  in  the  Second  Adjustment  of  the  Transit. 

The  centering  of  the  ocular-head  slide  in  the  case  of  tele- 
scopes having  a  fixed  objective,  as  in  the  higher  grades  of  in- 
struments, is  accomplished  in  the  same  manner  as  in  the  case 
of  the  objective  slide.  The  ocular-head  slide  carries  both 
ocular  and  cross-wires. 


THE    TELESCOPES    OF    ENGINEERING    INSTRUMENTS.  93 

The  centering  of  the  ocular  in  reference  to  the  cross-wires  is 
sometimes  arranged  for  by  means  of  a  special  set  of  screws. 
The  ocular  is  then  moved  until  the  cross-hairs  appear  in 
the  middle  of  the  field  of  view. 

Focusing  with  accuracy  is  necessary  not  only  for  clear  defi- 
nition, but  also  for  the  correct  use  of  the  telescope  as  a  means 
of  determining  direction.  In  its  completeness  it  involves  two 
operations : 

First,  it  requires  the  cross-wires  to  be  brought  into 
the  focus  of  the  eye-piece.  To  accomplish  this,  direct  the 
telescope  to  the  sky,  and  then  move  the  ocular  in  or  out 
very  carefully  until  the  most  distinct  vision  of  the  wires  re- 
sults. A  mean  position  between  the  points  of  equally  fair 
vision  of  the  wires  for  inward  and  for  outward  motion  of  the 
ocular  will  give  the  best  focusing  of  the  ocular. 

Secondly,  it  requires  the  cross-wires  to  be  brought  into  the 
focus  of  the  objective. 

To  accomplish  this,  either  move  the  objective  with  respect 
to  the  stationary  ocular-head,  which  carries  cross-threads  and 
eye-piece,  or  move  the  whole  ocular-head  with  respect  to  the 
stationary  objective,  until  there  is,  with  the  same  eye  as  em- 
ployed in  focusing  the  ocular,  the  most  distinct  vision  of  dis- 
tant objects. 

Parallax  of  the  wires,  or  an  apparent  displacement  of  the 
wires  with  respect  to  any  visible  object  upon  moving  the  eye 
in  front  of  the  ocular  up  and  down  or  to  the  right  and  left,  is 
due  to  the  wires  not  being  in  the  common  focus  of  objective 
and  eye-piece.  If  care  has  been  taken  to  focus  the  ocular 
accurately  on  the  threads,  the  parallactic  displacement  of  the 
wires  must  entirely  disappear  in  focusing  the  objective.  In 
fact,  this  disappearance  of  parallax  of  the  wires  is  the  best 
test  of  accurate  focusing. 

The  measurement  of  the  field  of  view  is  easily  accomplished 
by  either  of  the  following  methods:  (Y)  Select  two  distant 
points  which  appear  at  diametrically  opposite  edges  of  the 
field  of  view.  Measure  the  actual  distance,  */,  of  these  points 


9^..          THE    TELESCOPES   OF    ENGINEERING    INSTRUMENTS. 

from  each  other,  and  also  their  distance,  D,  from  the  tele- 
scope ;  then  the  field  is  expressed  in  minutes  of  arc  thus : 

Field  — 3438'  —. 

The  points  required  in  this  method  are  most  conveniently 
furnished  by  a  leveling  rod  placed  at  some  distance.  (2) 
Either  the  horizontal  or  vertical  circle  of  the  instrument  may 
be  used  for  directly  measuring  the  angular  distance  apart  of 
two  points  appearing  at  the  diametrically  opposite  edges  of 
the  field,  or  for  measuring  the  motion  of  a  point  throughout 
a  diameter  of  the  field.  A  knowledge  of  the  angular  value  of 
the  field  may  be  .of  assistance  in  roughly  estimating  angles 
and  distances. 

The  measurement  of  the  magnifying  power  of  a  telescope  may 
be  performed  in  several  ways. 

The  ordinary  two-eye  method  requires  the  telescope  to  be 
placed  at  a  great  distance,  as  compared  with  its  length,  before 
any  object  serving  as  a  scale  and  distinctly  visible,  to  the 
naked  eye.  As  object,  a  distinctly  visible  measuring-rod,  or 
even  the  regular  pattern  of  a  wall  may  answer.  Looking 
through  the  telescope  with  one  eye  and  viewing  the  scale 
directly  with  the  other,  two  superimposed  images  are  seen. 
If,  now,  n  divisions,  as  seen  with  the  telescope,  appear  to  cor- 
respond with  TV"  divisions  as  seen  with  the. naked. eye,  the  mag- 
nifying power,  M,  is 


The  inaccuracy  of  this  method  arises  from  the  impossibility 
of  securing  distinct  vision  with  the  naked  eye  of  an  object  at  a 
sufficiently  great  distance. 

Jordan's  method  has  the  advantage  over  the  usual  two-eye 
methods,  in  that  a  horizontal  axis  of  the  telescope  does  not 
interfere,  and-  that  both  eyes  are  adjusted  for  distinct  vision. 
Look  through  the  telescope  at  a  divided  rod,  or  at  some 
bright  object  of  known  size  projected  on  a  dark  background, 
and  hold  up  before  the  other  eye,  at  the  distance  of  distinct 


THE    TELESCOPES   OF    KN<  il  \KKRI  X(i    INSTRUMENTS.  95 

vision,  an  open  pair  of"  compasses.  Now  bring  the  points  of 
cue  compasses,  as  clearly  seen  with  one  eye,  into  apparent  co- 
incidence with  the  telescopic  image  of  the  rod  as  seen  with 
the  other  eye,  and  measure  off,  as  on  a  drawing,  the  apparent 
si/e  of  a  portion,  R,  of  the  rod,  and  afterward  find  this  distance 
apart,  i\  of  the  compass  points  by  means  of  a  divided  scale. 
The  distance  of  the  rod  from  the  eye  being  /?,  and  the  dis- 
tance of  the  compass  from  the  eye,  d,  the  magnifying  power, 
J/.  is  evidently  — 

M-  r-^*-rn 
~  d  '  D      Rd 

Valz's  method  is  both  neat  arid  easily  applied.  It  depends 
on  the  measurement  of  the  angle  which  the  rays,  coming  from 
an  object  of  known  angular  diameter,  form  on  issuing  from 
the  ocular  of  the  telescope.  The  sun,  on  account  of  its  bright- 
ness and  well-known  angular  diameter,  is  for  this  purpose  par- 
ticularly suitable.  Place  a  screen  at  a  distance,  D,  from  the 
"  eye-point,"  and  there  receive  the  solar  image,  whose  linear 
diameter  we  shall  call  d.  Let  also  s  be  the  true  angular 
diameter  of  the  sun,  and  5  the  angular  diameter  of  the  image 
on  the  screen,  subtended  at  the  eye-point,  then  — 

*  ^       d       dcot  i*s 


~tan.  y2  a        2D  tan.  l/2  S~         2.D 

And,  finally,  if  we  take  2  D  equal  to  cot.  y2  S, 

M=d. 

That  is,  if  the  double  distance,  2  D,  of  the  image  from  the  eye- 
point  is  taken  equal  to  the  cotangent  of  the  semi-diameter  of 
the  sun,  the  number  of  parts  of  the  scale  comprised  in  the  ex- 
tent of  the  image  will  express  the  magnification.  Thus,  in 
January,  the  image  should  be  received  and  measured  at  105 
scale  parts  from  the  eye-point,  in  April  and  October  at  107, 
and  in  July  at  109  parts. 

The  Gaussian  method  is,  all  considered,  the  most  scientific, 
but  requires  for  its  use  an  additional  instrument.  The  tele- 
scope whose  magnifying  power  is  to  be  determined  is  first 


96  THE    TELESCOPES    OF    ENGINEERING     INSTRUMENTS. 

carefully  focused  on  a  distant  object,  and  its  eye-end  is  then 
directed'  toward  some  well-illumined  object  of  regular  shape 
several  hundred  feet  distant  A  second  instrument  is  now  set 
up,  with  its  objective  turned  toward  the  objective  of  the  tele- 
scope whose  magnifying  power  is  desired.  The  object  will 
be  seen  through  both  instruments,  but  in  reduced  size,  and  its 
apparent  angular  size,  a,  is  measured  by  means  of  the  second 
instrument.  Afterward  the  angular  size,  A,  of  the  object  is 
measured  without  the  interposition  of  the  first  telescope.  The 
magnifying  power,  Mt  of  this  telescope  is  then  given  by  the 
expression  — 

M-    tan'  ^  A 
tan.  y2  a 

Example:  A  piece  of  white  card-board,  placed  at  a  distance 
of  several  hundred  feet,  subtends  an  angle,  A,  of  i°  30'  25", 
and  on  interposing  a  Wye  Level,  with  its  eye-end  directed 
toward  the  object,  the  apparent  angular  size,  a,  of  card,  is 
found  to  be  2r  30",  hence, 


J/of  the  Wye  Level  ="-"-'-  ^  (!°  3,°'  ^U  36.27    diameters. 

tan.  y2  (2'  30") 

QUEEN  &  Co.,  possessing  a  wide  experience  in  optical 
manufacture,  keep  pace  with  all  the  latest  scientific  improve- 
ments in  optical  glass  making,  and  aim  by  combining  the 
best  optical  theory  and  skill,  to  furnish  their  engineering 
instruments  with  telescopes  of  the  highest  excellence.  They 
have  no  peculiarity  of  their  telescopes  to  announce  except  it 
be  the  judiciously  planned  combination  of  aperture,  focal 
length,  power  and  qualities  of  glass  best  adapted  to  the  uses 
of  each  kind  of  instrument.  Good  seeing  capacity,  and  not 
the  particularly  high  power  with  its  concurrent  disadvantag4s, 
is  considered  of  the  foremost  consequence.  It  is  greatly  re- 
gretted that  the  necessary  limits  of  the  foregoing  article  have 
prevented  a  complete  exposition  of  the  theory  of  the  telescope. 
A  good-sized  volume  on  the  subject  would,  however,  seem 
inadequate,  and  serve  only  to  show  more  fully  and  clearly  in 
how  many  essentials  it  is  necessary  to  unite  optical  science 
with  experienced  skill  in  making  telescopes  that  are  adapted 
to  satisfactory  measurement  in  engineering. 


DESCRIPTION 

OF   THE 

ENGINEER'S   COMPASS. 


THE  following  description  of  the  Engineer's  Compass 
is  intended  to  direct  attention  to  its  various  parts 
and  forms. 

The  Tripod  furnished  with  the  engineer's  compass  is  either 
of  the  ordinary  round  leg  or  split  leg  form.  If  desired  a  head 
and  shoe  to  be  used  with  an  improvised  Jacob's  staff  is  also 
furnished. 

The  Ball-spindle,  on  which  the  socket  of  the  compass  is  fitted, 
is  of  conical  shape,  and  at  its  lower  end  turned  to  a  perfect 
sphere.  This  sphere  is  confined  in  a  socket  on  the  tripod 
head  in  such  a  manner  as  to  enable  the  compass  to  be 
brought  readily  to  an  approximately  level  position. 

The  Spring  Catch,  which  engages  in  a  groove  of  the  spindle 
of  the  compass  the  moment  ft  is  inserted  in  the  socket,  is 
attached  at  the  side  of  the  socket.  It  obviates  the  danger  of 
the  instrument  slipping  off  the  spindle  when  it  is  being  carried. 

The  Clamp  Screw,  by  means  of  which  the  spindle  of  the 
instrument  may  be  clamped  in  any  position,  is  placed  at  the 
side  of  the  socket  of  the  compass. 

The  Circle  of  the  Compass  is  graduated  to  half  degrees  and 
the  divisions  so  marked  as  to  be  read  with  the  greatest  ease. 
The  figuring  extends  from  o°  to  90°,  from  the  north  and  the 
south  points  in  both  directions.  The  line  of  zeros  passes 
through  the  vertical  axis  of  the  compass  and  is  also  in  line 
with  the  sights. 

The  Tangent  Screw  attached  to  the  circle  enables  the  line 
of  zeros  to  be  set  at  an  angle  with  the  sight  line  equal  to  the 
variation  of  the  magnetic  needle.  This  angle  is  measured  on 

97 


98  DESCRIPTION    OF    THE 

an  accessory  arc  or  circle,  placed  just  outside  the  clamp  and 
tangent  movement. 

The  Variation  Arc  or  Circle  is  placed  immediately  on  the  main 
plate  of  the  compass.  Its  centre  is  concentric  with  the  vertical 
•axis  of  the  instrument.  The  vernier  of  the  arc  or  circle  is 
usually  fastened  to  the  main  plate  while  the  arc  or  circle  plate 
forms  one  piece  with  the  graduated  compass  circle.  The  arc 
or  circle  is  used  for  setting  off  the  magnetic  declination  of  the 
place  so  as  to  enable  the  bearings  to  be  taken  with  respect  to 
the  true  astronomical  meridian.  When  a  complete  circle  is 
used,  as  in  the  railroad  compass,  horizontal  angles  may  be 
measured  with  it  for  any  purpose  whatever. 

The  Spirit  Levels  are  placed  directly  upon  the  plate  at  right 
angles  to  each  other  and  made  adjustable. 

The  Sights  are  vertical  standards  clamped  to  each  end  of  the 
plate  and  at  right  angles  to  it.  They  have  fine  slits  running 
through  nearly  their  entire  length.  Large  circular  apertures 
are  placed  at  intervals  along  the  slits  and  allow  a  distant 
object  to  be  the  more  readily  seen. 

The  north  sight  has  graduated  upon  its  lateral  edges  a  scale 
of  tangents  corresponding  to  a  circle  whose  centre  is  a  small 
eye-hole  placed  upon  the  south  sight  The  eye-hole  at  the 
lower  end  of  the  south  sight  is  intended  to  be  used  in  sighting 
for  angles  of  elevation,  the  eye-hole  at  the  top  of  the  same 
sight  being  used  for  angles  of  depression. 

The  Needle  Lifter  is  actuated  by  a  screw  placed  below  the 
main  plate.  The  needle  should  always  be  raised  from  its  centre 
pin  by  means  of  the  lifter  before  carrying  the  instrument. 

The  Out  Keeper  is  a  small  graduated  dial  turned  by  means 
of  a  milled  head  and  used  for  the  purpose  of  counting  the 
number  of  chains  measured. 

The  Brass  Cover  fitting  on  the  compass-box  is  intended  to  shield 
the  glass  cover  from  accidental  injury  during  transportation. 

The  Telescopic  Sight  is  an  appliance  consisting  substantially  of 
a  transit  telescope  with  its  fine  level  and  a  suitable  clamp  for 
attaching  it  at  right  angles  to  one  of  the  sighting  standards  of 
the  compass.  It  is  supplied  with  any  of  jthe  various  forms  of 
the  compass. 


ENGINEER  S    COMPASS.  99 

The  Forms  of  the  Compass  made  by  QUEEN  &  Co.  may  be 
best  understood  in  all  their  variety  by  reference  to  their  Cata- 
logue of  ^Engineering  Instruments.  The  following  are  the 
chief  forms : 

The  Plain  Compass  is  furnished  with  needles  of  four,  five,  or 
six  inches  in  length  but  has  no  variation  plate.  It  is  sometimes 
made  with  folding  sights  and  may  also  be  fitted  with  telescopic 
sights. 

The  Vernier  Compass  is  furnished  with  variation  arc  and  has 
the  tangent  scales  necessary  for  reading  angles  of  elevation  or 
depression. 

The  Railroad  Compass  has  the  'levels,  sights,  and  needle  of 
the  ordinary  Plain  Compass,  but  has  also  underneath  the  main 
plate  a  graduated  circle  by  means  of  which  horizontal  angles 
to  single  minutes  may  be  taken  independently  of  the  needle. 

The  Pocket  Compass  exists  in  a  great  variety  of  forms  and  is 
often  valuable  in  preliminary  rapid  work.  The  prismatic  com- 
pass of  Schmallcalder  deserves  to  be  particularly  mentioned 
among  hand  instruments.  The  graduated  card  of  this  com- 
pass is  attached  to  the  needle,  and  the  prism  permits  the  read- 
ing of  the  needle  to  be  made  simultaneously  with  taking  the 
sight. 

The  Solar  Compass  has,  in  addition  to  the  features  of  a  first- 
class  surveyor's  compass  with  full  graduated  circle  and 

verniers,  the  characteristic  devices  whose  chief  use  is  to  enable 

- 

the  surveyor  to  take  bearings  with  respect  to  the  true  or 
astronomical,  meridian.  These  devices  consist  essentially  of 
two  arcs,  one  called  the  latitude  arc,  with  a  movable  arm,  and 
set  at  right  angles  to  the  horizontal  plate  of  the  compass ;  and 
the  other,  a  declination  arc  placed  at  right  angles  to  an  arm 
with  an  axis  attached  perpendicular  to  it  and  revolving  in  a 
socket  carried  by  the  latitude  arm.  This  axis  lying  in,  or 
parallel  to,  the  planes  of  both  arcs  is  called  the  polar  axis,  and 
also  lies  in  or  parallel  to,  the  vertical  plane  containing  the  main 
line  of  sight  of  the  compass.  Its  use  and  adjustment  is 
referred  to  in  the  article  of  this  Manual  entitled.  "  The  Solar 
Transit  and  other  Methods  of  determining  the  Astronomical 
Meridian'' 


THE  ADJUSTMEiMTS 

OF   THE 

ENGINEER'S  COMPASS. 


THE  adjustments  of  an  engineer's  compass  may  be  treated 
of  as:  (i)  The  maker's  adjustment;  and  (2)  The  field 
adjustments.  The  latter  are  those  which  the  surveyor  finds  it 
necessary  and  convenient  to  verify  in  practical  work,  and  the 
former,  in  fact  inclusive  of  the  latter,  are  those  to  be  accu- 
rately accomplished  by  the  maker. 

THE  MAKER'S  ADJUSTMENTS. 

The  following  points  of  construction  and  adjustment  of  the 
Engineer's  Compass  must  be  accurately  attained  in  order  to 
realize  the  mathematical  conditions  of  the  problem. 

1.  The  main  plate  accurately  perpendicular  to   the  spindle 
of  the  compass. 

2.  The  variation   arc  or  circle  and  its  verniers  truly  gradu- 
ated and  concentric  with  the  spindle. 

3.  The  sights  and  sighting-slits  truly  at  right  angles  to  the 
main  plate. 

4.  The  line  joining  the   centre  of  the  sighting-slits  passing 
through  the  mathematical  axis  of  the  instrument. 

5.  The  zeros  of  the  verniers  of  the  variation  arc  or  circle  in  tfce 
same  straight  line  with  the  sights  and  axis  of  the  instrument. 

6.  The  compass  circle  truly  graduated,  its  centre  concentric 
with  the  axis  of  the  instrument,  and  its  line  of  zeros  coincident 
with  the  truly  adjusted  line  of  sights. 

7.  The  axis  of  each  of  the  plate  levels  at  right  angles  to  the 
axis  of  the  instrument. 

8.  The  pivot  of  the  compass  needle  coincident  with  the  ver- 

100 


ENGINEER'S  COMPASS.  101 

tical   axis   of  the   instrument,  and   sharp  enough   to   obviate 
appreciable  friction  in  the  needle-cap. 

9.  The  magnetic  needle  magnetically  sensitive  and  perfectly 
straight. 

10.  The   magnetic  axis  of  the   needle  coincident  with  the 
axis  of  form. 

1 1 .  The  magnetic  needle  adj  usted  for  the  magnetic  dip  of 
the  place  of  observation. 

12.  The  axis  of  the  suspended  plumb  bob  coincident  with 
the  vertical  axis  of  the  instrument. 

It  is  not  intended  that  the  foregoing  shall  represent  an  ex- 
haustive statement  of  the  details  requiring  the  attention  of  the 
skilled  maker,  but  it  is  hoped  that  this  statement  may  direct 
attention  to  essential  features  of  construction  otherwise  likely 
to  be  overlooked  by  purchasers  and  users  of  the  instrument. 

THE    FIELD    ADJUSTMENTS. 

The  following  methods  for  practically  detecting  and  correct- 
ing the  errors  of  adjustment  of  an  Engineer's  Compass  are 
given  for  field  use : 

First  Adjustment : — To  make  tJic  axis  of  the  plate  levels  pcr- 
pcudicular  to  tlic  vertical  axis  of  the  instrument. 

DETECTION  OF  THE  ERROR. — Carefully  level  the  instrument 
in  the  two  directions  parallel  with  the  levels.  Note  some  point 
seen  through  the  sights,  and  turn  the  sights  exactly  through 
1 80°,  or  until  the  same  point  is  'again  in  line.  Now  examine 
each  of  the  levels  in  turn,  and  see  if  there  has  been  any  dis- 
placement of  the  bubble.  The  amount  of  bubble  displacement 
is  in  each  case  just  double  the  error  of  the  bubble-tubes,  as 
already  explained  under  "  First  Adjustment"  of  the  Engineer's 
Transit. 

CORRECTION  OF  THE  ERROR. — By  means  of  the  screws 
near  the  ends  of  the  level-tubes,  carefully  bring  back  the  bub- 
ble through  half  the  displacement,  taking  care  to  have  the 
screws  fairly  tightened  when  done.  The  remaining  half  of  the 
bubble  displacement,  being  due  to  lack  of  horizontality  of  the 
plate,  may  now  be  corrected  by  leveling  up  the  instrument. 


102  THE    ADJUSTMENTS    OF    THE 

Second  Adjustment  :-^-  To  bring  the  pivot  of  the  magnetic 
needle  into  coincidence  witk  the  axis  of  the  instrument. 

DETECTION  OF  THE  ERROR. — Bring  one  end  of  the  needle 
on  a  division  of  the  circle,  and  note  the  deviation  of  the  other 
end  from  the  division  making  180°  with  it.  Then  remember 
that  this  deviation  from  a  true  reading  may  be  due  to  any  one 
or  all  of  the  following  defects  : 

(i.)  Errors  of  graduation  in  the  circle. 

(2.)  Eccentricity  of  the  circle  with  respect  to  axis  of  instru- 
ment. 

(3.)  Bent  needle. 

(4.)  Eccentricity  of  the  pivot  with  respect  to  axis  of  instru- 
ment. 

The  first  two  errors,  if  they  exist,  cannot  be  adjusted  by 
the  engineer,  and  they  are  here  assumed  as  negligible  errors. 
This  reduces  the  causes  of  the  deviation  mentioned  to  the  two 
last  named.  But  in  order  to  determine  the  nature  of  the  errors 
fully,  readings  must  be  made  round  the  circle  at  intervals,  say, 
of  15°,  and  the  end  deviations  noted.  Then, 

(i.)  Constant    difference    between   end    readings   of   needle 

f  Needle  bent,  and 
means  < 

I  Pivot  centered. 

(2.)  Variable    difference   between    end    readings  of  needle 

(  Pivot  eccentric,  and 

means  <  f  straight,  if  difference  is  zero  for  any  one 

(needle  either  J       direction;  or 

(  bent,  if  difference  is  never  zero. 

This  is  made  evident  by  (A),  (B),  and  (C),  of  Fig.  49. 
Fig.  (A)  illustrates  case  (i)  of  pivot  centered  and  needle 
bent,  the  differences  S  a,  E  b,  etc.,  always  remaining  constant. 
Fig.  (B)  illustrates  the  case  of  straight  needle  and  eccentric 
pivot,  the  difference  of  end  readings  becoming  zero,  say  for  the 
position  WE,  where  the  straight  needle  cuts  both  pivot,  D,  and 
centre  of  circle,  C ;  and  the  difference  being  at  its  maximum, 
vS"  a,  at  90°  from  the  position  of  zero  difference.  Fig.  (C) 
illustrates  the  case  of  eccentric  pivot  and  bent  needle;  5  a 


ENGINEERS    COMPASS.  103 

being  the  maximum  ;  and  E  b  the  minimum  difference  of  the 
end  readings. 

CORRECTION  OF  THE  ERROR. — Find  the  position  of  the  maxi- 
mum difference  of  end  readings,  S  a,  Fig.  49,  (C),  and  also  the 
minimum,  E  b.  Take  one-half  the  difference  of  these  differ- 
ences, and  adjust  the  pivot  through  this  amount  at  right  angles 
to  the  position  of  maximum  deviation.  . 

Another  method  of  correction  proceeds  as  follows : 

(i.)  Temporarily  adjust  pivot  so  as  to  allow  needle  in  some 
position  to  cut  diametrically  opposite  graduations.  Reverse 
and  thus  double  the  error  due  to  bent  needle.  Straighten 
needle  by  bending  through  one-half  this  difference. 

(2.)  Adjust  pivot  till  at  all  intervals,  say,  of  30°,  the  needle 
points  to  opposite  divisions. 


N 


(B.)  (C.) 

Fig.  49- 

Third  Adjustment: — To  straighten  the  magnetic  needle. 

DETECTION  OF  THE  ER£OR. — This  has  already  been  for  the 
most  part  explained  under  the  head  of  the  Second  Adjustment. 
It  is  only  necessary  here  to  remark  that  the  minimum  devia- 
tion, E  b,  Fig.  49,  (C),  is  altogether  due  to  the  bent  needle. 

CORRECTION  OF  THE  ERROR. — Having  found  the  position  of 
the  minimum  deviation  of  end  readings,  Eb,  Fig.  49,  (C),  bend 
the  needle  carefully  near  the  centre  to  an  amount  equal  to  Eb- 

Fourth  Adjustment: — To  make  the  plane  of  the  sights  per- 
pendicular to  the  plane  of  the  levels. 

DETECTION  OF  THE  ERROR. — Carefully  level  the  instrument 
and  bring  the  plane  of  sights  upon  a  plumb-line  suspended  at 
some  convenient  distance.  Sight  by  looking  through  lower 


104         THE    ADJUSTMENTS    OF    THE    ENGINEER'S    COMPASS. 

part  of  one  sight,  and,  running  the  eye  along  the  other,  note 
the  latter's  deviation  from  the  vertical  plumb-line.  Similarly 
test  the  other  sight. 

CORRECTION  OF  THE  ERROR.- — Any  error  of  this  sort  can  he 
corrected  satisfactorily  only  by  the  maker.  Temporary  relief 
may  be  had  by  clamping  under  the  sides  of  the  sighting  stand- 
ards thin  bits  of  paper,  so  as  to  bring  the  sights  truly  vertical. 

Several  other  important  points  in  the  maker's  work  may  also 
be  easily  tested  : 

( I .)  To  test  whether  the  diameter  passing  through  the  zero 
graduations,  or  the  "  line  of  zeros,"  lies  in  the  plane  of  the 
sights.  Set  the  declination  arc  carefully  to  zero,  and  stretch 
two  fine  hairs  vertically  in  the  centre  of  the  slits,  and  note  if 
the  zeros  are  in  line. 

(2.)  To  test  whether  the  line  of  sight  passes  through  the 
centre,  sight  to  a  very  near  object,  and  read  one  end  of  needle. 
Reverse  and  read  same  end  of  needle.  One-half  the  difference 
of  the  readings  is  the  error  due  to  the  eccentricity  of  the  line 
of  sights.  One-half  the  sum  of  the  same  readings  is  the  true 
reading.  Also,  if  both  ends  of  needle  are  read,  and  one-half 
the  sum  taken,  the  eccentricity  of  the  sight  line  is  eliminated. 

(3.)  The  magnetic  sensitiveness  of  the  needle  may  be  tested 
by  setting  the  needle  in  vibration  by  approaching  and  remov- 
ing some  iron  piece,  and  then  noting  whether,  upon  repeated 
trials,  the  needle  returns  precisely  to  the  same  point.  If  not, 
the  pivot  is  either  dull  or  the  needle  lacks  directive  force,  and 
must  be  remagnetized. 

(4.)  The  absence  of  metal  in  the  compass  capable  of  affect- 
ing the  needle,  may  be  verified  by  slowly  turning  the  instru- 
ment about  its  axis  and  noting  whether  or  no  the  needle  is  in 
any  position  slightly  carried  along. 

(5.)  The  horizontal  swinging  of  the  needle  is  affected  by  the 
Magnetic  Dip,  and  is,  with  other  matters  pertaining  to  mag- 
netism, explained  in  the  article  of  this  Manual,  entitled,  "  Ter- 
restrial Magnetism  in  its  Relation  to  Surveying  Instruments" 

QUEEN  &  Co.  invariably  test  the  mechanical  perfection  of 
their  instruments  by  giving  them,  finally,  a  thoroughly  com- 
plete adjustment. 


TERRESTRIAL  MAGNETISM 

IN    ITS    RELATION    TO 

SURVEYING  INSTRUMENTS. 


THE  earth  acts , on  magnetic  substances  placed  on  its 
surface  very  much  as  though  it  were  itself  a  great 
magnet.  One  pole  of  this  huge  magnet  is  near  the  earth's 
North  Pole,  the  other  near  its  South  Pole.  If  the  magnetic 
condition  of  the  earth  were  of  an  entirely  constant  nature,  the 
surveyor  should  need  nothing  better  than  a  freely-suspended 
magnetic  needle  directed  by  terrestrial  magnetism,  to  give  him 
a  zero  line,  namely,  the  magnetic  meridian,  from  which  to 
measure  his  angles.  But  terrestrial  magnetism  is  a  very 
variable  thing,  and  moreover  bears  peculiar  relations  to  the 
needle  of  the  surveying  instrument.  It  is,  therefore,  desirable 
to  give  a  brief  explanation  of  these  fundamental  relations. 

Terrestrial  magnetism  may  be  studied  by  noting  its  action  on 
a  freely-suspended  magnetic  needle.  The  three  factors  usually 
measured  are  the  Magnetic  Intensity,  the  Dip  of  the  needle, 
and  the  Declination  of  the  needle.  If  a  long  steel  knitting- 
needle  of  the  old-fashioned  type  be  suspended  by  a  fine  thread 
attached  to  its  middle,  it  will  when  uifmagnctizcd,  direct  itself 
in  some  position  in  a  horizontal  plane  determined  by  the  slight 
torsion  of  the  thread.  On  being  magnetized,  it  will  direct 
itself  differently.  In  the  first  place,  instead  of  being  horizontal 
its  north  end  will  now  incline  downwards.  The  angle  made 
by  the  north  end  of  the  needle  with  the  horizon,  is  called  the 
angle  of  Dip  or  of  Inclination.  In  the  second  place,  it  will  be 
noticed  that  this  magnetized  needle  also  directs  itself  in  a  plane 
which  is  nearly  north  and  south.  The  angle  which  the  north- 
south  plane  of  the  magnetic  needle  makes  with  the  true  north7 
south  plane  is  called  the  Declination  of  the  needle.  This 
angle  is  also  sometimes  called  the  Variation  of  the  needle, 

105 


106  TERRESTRIAL    MAGNETISM    IN    ITS 

although  this  designation  is  both  antiquated  and  misleading. 
Finally,  the  force  with  which  the  needle  will  direct  itself  in  the 
magnetic  meridian  when  disturbed  from  it  is,  other  things 
being  equal,  determined  by  the  Strength  of  the  Earth's  magnet- 
ism, or  by  the  Magnetic  Intensity.  We  shall  now  take  up 
each  of  these  terrestrial  magnetic  elements  and  show  their 
practical  relation  to  the  surveyor's  needle. 

I.  The  magnetic  intensity  or  magnetic  strength  of  any  "  field  " 
is  proportional  to  the  square  of  the  number  of  vibrations  made 
in  the  unit  of  time,  by  any  magnetic*  needle  placed  in  that 
"  field."  Vibrating  the  same  magnetic  needle  at  different 
places  or  in  different  "  fields,"  the  intensity  of  the  earth's 
magnetism  will  vary  as  square  of  the  number  of  vibrations 
made  at  each  place  in  the  unit  of  time.  The  Intensity,  spoken 
of  without  qualification,  is  considered  as  taken  in  the  direction 
of  the  earth's  magnetic  force,  or  in  the  line  of  dip.  The  earth's 
action  on  a  horizontal  needle  is  of  course  the  horizontal  com- 
ponent of  the  intensity.  If,  I,  denote  the  Magnetic  Intensity, 
H,  its  horizontal  component,  V,  its  vertical  component,  and  D, 
the  angle  of  Dip  or  Inclination  .  below  the  horizon,  then 
evidently 

H=  /cos  D 
and  V  =  /sin  D. 

The  magnetic  moment  of  the  needle  combined  with  the 
strength  of  the  earth's  magnetic  field  determines  the  force  with 
which  the  needle  tends  to  direct  itself  in  the  magnetic  meridian. 
The  magnetic  moment,  M,  of  the  needle  is  equal  to  the  product 
of  the  "  magnetic  mass,"  ;;z,  of  one  of  its  poles  by  the  length,  /, 
of  the  needle,  or,  M  =  ml.  A  magnetized  needle  movable 
about  a  vertical  axis,  as  in  the  case  of  the  surveyor's  compass, 
obeys  the  horizontal  component,  H,  of  the  earth's  magnetic 
force,  and  directs  itself  so  that  its  axis  of  magnetization  is  in  the 
magnetic  meridian.  If  the  needle  is  turned  out  of  the  meridian 
through  an  angle  d,  the  moment  of  the  couple  tending  to 
bring  it  back  is  expressed  by 

m  I  //sin  d. 
The  sensitiveness  of  the  needle  is  measured  by  the  accuracy 


RELATION    TO    SURVEYING     INSTRUMENTS.  107 

with  which  it  returns  to  the  same  position  after  displacement 
from  its  natural  direction  in  the  meridian.  From  the  foregoing 
expression  it  is  seen  that,  so  far  as  the  needle  is  concerned,  the 
amount  of  magnetization,  ;;/,  and  the  length,  /,  combine  to  make 
its  magnetic  moment  effective  in  any  given  magnetic  field. 
Acting  against  the  moment  tending  to  direct  the  needle,  is  the 
friction  on  the  centre-pin  or  pivot.  And,  hence,  with  a  needle 
lacking  sensitiveness,  it  is  a  question  either  of  sharpening  the 
centre-pin  and  thus  reducing  the  friction,  or  of  increasing  the 
magnetization,  m,  by  remagnetizing  the  needle.  When  the 
needle  is  deflected,  as  by  bringing  near  it  a  bit  of  iron,  it  should 
always  return  to  the  original  position  within  a  few  minutes  of 
arc. 

The  magnetization  of  the  needle,  or  the  increase  of  the 
magnetic  mass,  m,  is  accomplished  by  stroking  the  needle 
with  a  good  permanent  magnet  in  the  following  manner : 
With  the  south  pole  of  the  magnet  approach  the  middle  of 
the  needle  in  a  direction  at  right  angles  to  it,  and  then  pass 
this  south  pole  along  the  neeedle  toward- the  north  pole  of  the 
needle  and  beyond  it,  returning  by  circular  sweep  to  the  mid- 
dle again.  Repeat  this,  say,  twenty  times.  Similarly  stroke 
the  south  end  of  the  needle  with  the  north  pole  of  the  magnet. 
The  needle  may  thus,  in  a  few  minutes,  be  magnetically 
saturated. 

The  conservation  of  the  needle's  magnetism  depends  on  its 
original  proper  tempering,  its  freedom  from  subsequent  jars, 
and  its  remaining  when  unused  in  the  normal  position  in  the 
magnetic  meridian. 

II.  The  Magnetic  Inclination  or  Dip  is,  as  already  explained, 
the  angle  made  with  the  horizon  by  the  north  end  of  the  freely- 
suspended  needle.  The  tendency  of  the  north  end  of  the  needle 
to  dip  increases  as  we  go  north  until  the  magnetic  pole  is 
reached,  where  the  free  needle  occupies  a  vertical  direction.  It 
is  on  account  of  this  variableness  of  the  Dip  that  the  surveyor's 
needles  usually  have  wound  round  the  south  end  a  small  bit  of 
wire  whose  position  may  be  varied  so  as  to  bring  the  needle 
into  a  horizontal  position  at  the  place  the  instrument  is  set  up 
for  use.  It  is  for  the  same  reason,  therefore,  to  be  borne  in 


108  TERRESTRIAL    MAGNETISM    IN    ITS 

mind  that  however  accurately  the  needle  may  be  adjusted  to  a 
horizontal  position  by  the  maker  in  his  locality,  it  will  require 
careful  adjustment  by  the  surveyor  for  the  Dip  of  the  place  of 
observation,  if  it  be  at  any  considerable  distance  from  the  place 
of  original  adjustment.  The  Dip  may  vary,  also,  at  any  given 
place,  on  account  of  the  prevalence  of  some  unusual  magnetic 
disturbance. 

The  dipping  needle  is  a  magnetic  needle  suspended  on  a 
horizontal  axis,  and  free  to  move  only  in  a  vertical  plane.  If 
the  plane  of  this  needle  be  brought  into  the  magnetic  meridian 
its  north  end  will  incline  downwards,  and  the  angle  of  Dip  may 
be  read  off  on  the  circle.  If,  as  the  dipping  needle  is  kept  in 
the  plane  of  the  magnetic  meridian  the  angle  of  Dip  changes 
as  the  observer  moves  along,  it  is  an  indication  of  attractive 
force  due  to  beds  of  iron  ore.  It  is  evident  that  the  unwonted 
dipping  of  a  previously  well-adjusted  surveyor's  needle  may 
be  due  to  the  same  cause. 

III.  The  Magnetic  Declination  or  Variation  is  the  angle  made 
by  the  free  magnetic  needle  with  the  astronomical  meridian,  or 
true  north-south  plane.  The  term  Variation,  though  almost 
out  of  use,  still  survives  in  the  "  variation  plate  "  of  the  sur- 
veyor's compass.  This  magnetic  element  of  the  earth  has  by 
far  the  most  important  relation  to  the  surveyor's  work,  and 
requires  detailed  explanation. 

The  determination  of  the  declination  of  the  magnetic  needle 
for  a  given  place  and  time,  has  often  to  be  undertaken  by  the 
surveyor.  Since  this  requires  a  knowledge  of  the  direction  of 
the  astronomical  or  true  meridian,  the  subject  is  referred  to  in 
the  article  of  this  Manual,  entitled,  "  The  Solar  Transit  and 
Methods  of  Determining  the  Astronomical  Meridian! 

The  variations  of  the  Declination  are  numerous  and  of  a  very* 
complicated  nature.  The  direction  of  the  needle  changes  from 
hour  to  hour  through  the  day,  from  month  to  month  through 
the  year,  and  from  year  to  year  through  the  centuries.  In 
addition,  it  is  subject  to  extraordinary  disturbances  during 
magnetic  storms.  These  special  disturbances  aside,  the  laws 
of  the  periodic  changes  in  the  declination  have  been  fairly  well 
established,  and  the  surveyor  is  often  obliged  to  have  recourse 


RELATION    TO    SURVEYING    INSTRUMENTS.  1 09 

to  these  observed  laws.  It  is  fortunate  that  in  our  own  coun- 
try the  study  of  terrestrial  magnetism  has  been  an  important 
part  of  the  work  of  the  Coast  and  Geodetic  Survey.  Professor 
Charles  A.  Schott,  the  able  scientist  in  charge  of  the  discussion 
of  the  magnetic  observations,  has,  in  the  Survey  Reports, 
during  many  years,  published  comprehensive  papers  of  the 
highest-  value  to  the  surveyor  in  the  solution  of  problems 
involving  changes  in  the  declination  of  the  needle. 

Irregular  variations  accompanying  so-called  "  electric  storms," 
are  undoubtedly  in  close  relation  with  changes  in  the  sun,  and 
its  spots.  Auroras  frequently  occur  at  the  same  time.  Since 
these  extraordinary  deflections  of  the  needle  from  the  normal 
positions  may  either  be  limited  to  a  few  minutes  of  arc,  or 
ampunt  to  several  degrees,  the  careful  observer  must  be  con- 
tinually on  the  alert.  The  verification  of  a  "  magnetic  storm  " 
would  be  ample  excuse  to  await  its  subsidence,  before  trusting 
the  indications  of  the  magnetic  needle. 

The  small  periodic  variations  which  require  no  attention  on 
the  part  of  the  surveyor,  are  the  annual  variation  of  the  decli- 
nation, its  amplitude  being  at  most  one  and  a  half  minutes  of 
arc  ;  the  solar  rotation  variation  having  a  period  of  about  26 
days,  and  of  very  small  amplitude ;  and  the  lunar  variations, 
the  diurnal  one  exhibiting,  like  the  tides,  two  maxima  and 
minima  each  lunar  day,  and  having  a  range  at  Philadelphia  of 
about  27",  the  other  lunar  inequalities  being  of  still  smaller  order. 

The  Solar-diurnal  variation  is  a  systematic  angular  movement 
of  the  direction  of  the  magnetic  needle,  having  for  its  period 
the  Solar  day.  The  amount  of  this  daily  swing  of  the  needle 
is  on  the  average  about  8',  the  north  end  having  its  extreme 
easterly  position  about  8  A.  M.,  its  extreme  westerly,  about 
1.30  P.  M.,  and  its  mean  position  about  10.30  A.  M.  and  8  p.  M. 
This  daily  variation  of  the  needle  is  not  exactly  the  same  for 
different  places  and  seasons,  but  the  following  table,  correct  to 
the  nearest  tenth  of  a  minute  of  arc  for  Philadelphia,  presents  a 
good  average  for  the  United  States.  It  is  derived  from  Appendix 
8,  of  the  Report  of  the  United  States  Coast  and  Geodetic  Survey 
of  1 88 1 .  For  the  surveyor  this  diurnal  variation,  and  the  secular 
variation,  presently  to  be  described,  are  particularly  important. 


no 


TERRESTRIAL    MAGNETISM    IN    ITS 


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The  correction  of  observed  bearings  to  the  daily  mean  posi- 
tion of  the  needle  is  readily  effected  by  adding  or  subtracting 
the 'numbers  of  this  table,  irrespective  of  the  signs,  according 
to  the  following  rule:  Before  n  a.  m.  subtract  the  tabular 
minutes  from  N.  W.  and  S.  E.  bearings  and  add  them  to  N.  E. 
and  S.  W.  bearings  ;  after  n  a.  m.  add  the  tabular  minutes  to 
N.  W.  and  S.  E.  bearings  and  subtract  them  from  the  N.  E. 
and  S.  W.  bearings. 

The  secular  variation  of  the  magnetic  declination  is  probably 
of  a  periodic  character,  but  requires  several  centuries  for  the 
completion  of  a  cycle.  During  many  years,  therefore,  the 
movement  of  the  needle  is  progressively  in  one  direction. 
The  amount  of  the  annual  change  of  declination  varies  for 
different  places  and  times,  and  it  is  on  this  account  that  over 
nearly  the  whole  of  the  United  States  the  effect  of  the  secular 
variation  is,  at  present,  to  increase  the  west  declinations  or 
decrease  the  east  declinations  ;  that  is,  the  needle  is  moving 
westward.  On  parts  of  the  Pacific  coast  the  effect  is  opposite, 
the  needle  there  moving  in  an  easterly  direction. 

The  annual  change  in  declination,  as  already  intimated,  varies 
slightly  from  year  to  year.  Its  approximate  value  for  any 
given  locality  may  be  taken  from  the  accompanying  map  of 
Isogonic  Lines,  upon  which  also  the  amount  of  the  annual 
change  for  the  epoch  and  place  have  been  noted.  A  plus  sign 
in  the  annual  change  indicated  increasing  west  declination  or 
decreasing  east  declination,  and  a  minus  sign  increasing  east 
or  decreasing  west  declination. 

The  Isogonic  Lines  for  any  given  epoch  are  imaginary  lines 
on  the  surface  of  the  earth  joining  points  whose  declination 
are  at  that  time  equal.  An  agonic  line  is  one  joining  points 
of  zero  magnetic  declination  or  points  where  the  magnetic 
meridian  coincides  with  the  astronomical  meridian. 

The  Isogonic  Chart  which  accompanies  this  article  is  a 
reduction  of  that  of  the  United  States  Coast  and  Geodetic  Sur- 
vey for  1890,  the  latest  published.  The  approximate  declina- 
tion for  any  place  may  either  be  directly  taken  from  it  or 
inferred  by  simple  interpolation. 

The  Table  of  Formulae  which  follows  is  the  result  of  an  ex- 


112  TERRESTRIAL    MAGNETISM    IN    ITS 

tended  investigation  by  Professor  Charles  A.  Schott  and  pub- 
lished in  the  United  States  Coast  Survey  Report  for  1888. 
These  formulae  are  the  best  known  statement  of  the  law  of 
change  of  the  declination  for  the  given  stations.  The  letter  D 
in  the  last  column  stands  for  declination,  a  plus  sign  indicating 
west  declination ;  a  minus  sign,  east  declination.  The  letter 
;//  stands  for  the  time,  expressed  in  years  and  fraction  of  a 
year,  which  has  elapsed  since  1850;  or,  in  other  words,  is 
equal  to  t — 1850.  Although  the  formulae  are  strictly  only 
true  for  any  time  within  the  limits  of  observation,  always,  prior 
to  1888,  they  may  also  be  used  for  estimations  beyond  these 
limits.  As  illustrative  of  the  use  of  the  expressions,  the 
following  steps  in  the  computation  of  the  declinations  for 
Philadelphia  and  Denver  for  July  1st,  1893,  are  given.  The 
only  points  that  need  to  be  specially  noted  are  that  care  must 
be  exercised  in  properly  taking  out  the  sines  of  angles 
greater  than  180°,  and  that  the  parts  of  a  year  are  to  be  ex- 
pressed fractionally,  as,  for  example,  in  our  case,  1893.5.  The 
value  of  m  is  then  1893.5  — 1850=  43.5.  It  will  not  harm 
again  to  remind  the  reader  that  values  of  the  declination, 
whether  taken  from  the  map  or  derived  from  the  formulae, 
are  liable  to  considerable  erfor,  and  that  observation  can  alone 
yield  accurate  results. 

PHILADELPHIA  : 
D=+'5.36°  +  3-17  sin    (1.50°  X  43-5 -26.1°)  +0.19  sin 

(4-0°  X  43-5 +  H60). 

D=  +  5-36°  +  3-17  sin  39.15°  +  0.19  sin  320°. 
D  =-.  -f-  5.36°  +  3.17  sin  39°  9'  —  0.19  sin  40°. 

D  =  +  5.36°  +  2.00°—  0.12°. 

D  = -f-  7.24°,  /.  e.,  west  declination. 
DENVER  : 

D  =     -  15-30°  +  o.oi  i°  X  43-5  +  0.0005°  (43-S)2- 

D  =  — 15.30°  +  1.42°. 

D  —  —  13.88°,  i.  e.,  east  declination. 


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QUEEN"  PRECISION  LEVEL. 


A  1526. 


Price,  $250.00 


DESCRIPTION 


OF  THE 


ENGINEERS'  LEVEL. 


THE  Engineers'  Level  consists  essentially  of  a  horizon- 
tally-directed  telescope   combined  with  a  spirit-level 
parallel  with  it,  and  the  whole  suitably  supported  on, 
and  capable  of  revolution  about,  a  vertical  axis. 

The  telescope  of  the  Engineers'  Level  is  usually  of  a  longer 
focus,  of  larger  aperture,  and  of  higher  power  than  that  of  the 
transit.  A  full  description  of  the  optical  characteristics  of  the 
telescope  will  be  found  in  the  article  entitled  "  The  Telescopes 
of  Engineering  Instruments" 

The  cross  hair-ring  is  usually  provided  with  two  threads,  one 
horizontal  and  the  other  vertical,  the  ring  being  adjustable  for 
the  horizontality  and  verticality  of  these  threads.  Sometimes 
stadia  wires  are  added  for  conveniently  reading  off  distances 
on  the  rod. 


Fig.  50. 

The  ocular  slide,  Fig.  50,  is  provided  with  a  set  of  centering- 
screws  accessible  from  the  outside  of  the  telescope.  The  process 
of  centering  the  eye-piece  can  thus  be  accomplished  with  con- 
venience. The  eye-tube  is  moved  in  and  out  by  means  of  a 
smoothly-working  screw  adjustment,  which  obviates  any  dis- 
turbance of  the  telescope  and  permits  the  focusing  on  the 
hairs  to  be  performed  with  great  accuracy. 

119 


120  ENGINEERS     LEVEL. 

The  object  slide  is  covered  by  a  protector.     The  set  of  ad- 
justing screws  at  the  middle  of  the  telescope  and  accessible 
from  the  outside  are  intended  for  centering  the  object-glass  . 
and  its  slide  with  respect  to  the  mechanical  axis  of  the  tele- 
scope. 

A  rack  and  pinion  movement  is  attached  to  the  object-slide 
Tind  operated  by  a  milled  head  placed  near  the  middle  qf  the 
telescope. 

The  sun-shade  is  an  open  brass  cap  supplied  with  every  level 
and  always  to  be  used  for  the  best  results. 

The  collars  or  rings  fitting  on  the  telescope-tube  and  sup- 
porting it  when  resting  on  the  wyes,  are  usually  about  twelve 
inches  apart.  They  are  made  of  the  hardest  bell  metal  and 
very  accurately  turned  to  exactly  the  same  diameter. 

The  wyes  upon  which  the  collars  rest  are  made  of  the  best 
bell  metal  and  shaped  to  precise  similarity.  They  are  each 
attached  to  the  level-bar  by  means  of  two  adjustable  nuts. 
The  telescope  is  held  firmly  in  position  by  clips  fastened  by 
means  of  pins.  In  order  to  insure  the  correct  position  of  the 
cross-wires  a  small  projecting  piece  extends  from  the  telescope 
and  is  brought  in  contact  with  a  similar  piece  attached  to  one 
of  the  wyes. 

The  level  bar,  made  of  the  best  bell  metal,  is  usually  of 
square  cross-section,  and  has  attached  to  its  middle  the  inner 
axis  or  "  centre  "  of  the  instrument. 

A  vertical  micrometer  screw  with  graduated  head  is,  in  the 
finest  grade  of  leveling  instruments,  attached  to  one  end  of  the 
level-bar  for  the  purpose  of  setting  the  bubble  in  refined  work.* 

The  centres,  Fig.  51,  are  compound;  the  inner  one  attached  to 
the  level-bar  is  a  long  cone,  of  the  hardest  bell  metal  and  held 
in  place  by  means  of  the  centre  screw  placed  at  its  lowest  ex- 
tremity ;  the  outer  "  centre  "  is  made  of  hard  red  metal  and 
fits  into  the  socket  of  the  leveling  head.  Both  "  centres  "  are 
accurately  turned  in  the  lathe  between  dead  centres.  The 
three  metals  used  respectively  for  the  inner  centre,  the  outer 
centre,  and  the  socket  of  the  leveling  head  are  selected  so  as 


DESCRIPTION     OF    THE 


121 


to  secure  the  smallest  coefficient  of  friction  and  great  dura- 
bility. 

The  clamp  and  tangent  movement  is  attached  to  the  inner 
44  centre,"  and  is  of  the  same  form  as  that  supplied  with  QUEEN 
&  Co.'s  engineering  transits. 

The  leveling  head  has  the  usual  plates  and  leveling  screws, 
as  shown  in  the  foregoing  section.  It  is  usually  clamped  to 
the  tripod  head. 

The  fine  spirit-level,  of  about  eight  inches  in  length,  is  usually 
attached  below  the  telescope,  and  furnished  with  adjusting 
screws  which,  at  one  end  of  the  level  tube,  permit  lateral  or 


Fig-  51- 

horizontal  motion,  and,  at  the  other  end,  vertical  motion.  In 
some  forms  of  the  leveling  instrument  it  is  found  advantageous 
to  place  the  spirit-level  above  the  telescope.  For  a  complete 
description  of  the  spirit-level,  its  construction  and  theory,  the 
reader  is  referred  to  the  article  of  this  Manual  entitled  "  The 
Spirit-levels  of  Engineering  Instruments" 

A  reflector  is  sometimes  attached  for  the  purpose  of  allow- 
ing the  position  of  the  bubble  to  be  read  from  the  eye-end  of 
the  telescope,  without  change  of  position  of  the  observer.  If 
the  spirit-level  is  below  the  telescope,  the  reflector  is  attached 
at  the  side ;  if  above  the  telescope,  the  reflector  is  mounted 
over  it. 


122  ENGINEERS      LEVEL. 

The  Forms  of  the  Level  range  from  the  Simple  Dumpy  Level 
through  various  styles  of  the  Engineers'  Level  to  the  higher 
types  of  the  Precision  Level.  The  following  are  taken  as  rep- 
resenting the  chief  classes : 

The  Dumpy  Level  is  a  compact  instrument  possessing  the 
smallest  number  of  adjustments,  and  is  hence  least  liable  to 
derangement  from  rough  usage.  It  is  without  wyes,  and  its 
telescope  tube  forms  one  rigid  piece  with  the  level-bar.  Only 
the  line  of  sight  and  the  spirit-level  are  adjustable  by  the  en- 
gineer. With  intelligent  usage,  the- QUEEN  &  Co.  Dumpy 
Level,  made  in  a  large  and  powerful  form,  is  often  capable  of 
results  equal  to  those  secured  by  the  more  complicated  wye 
level. 

The  Architects'  Level  is  a  small  "level  of  the  wye  form,  fur- 
nished with  a  horizontal  circle^  and  hence  adapted  to  many 
kinds  of  building  and  city  work,  One  form  of  it,  called  the 
"Architect's  Compass  Level,"  i#  fitted  with  a  compass-box,  in 
addition  to  the  horizontal  circle. 

The  Engineers'  Wye  Level  is  the  one  we  have  taken  as  rep- 
resenting the  general  type  in  the  foregoing  description,  and  is 
made  in  several  sizes  and  /orms. 

When  furnished  with  a  level  mirror  and  a  graduated  mi- 
crometer screw  for  varying  the  inclination  of  the  telescope  with 
respect  to  the  level  axis,  it  is  adapted  to  the  higher  methods 
of  manipulation  required  in  hydrographic  and  other  precise 
work. 

The  Precision  Level,  adapted  to  the  highest  grade  of  leveling, 
is  furnished  with  the  requisites  for  testing  the  performance  of 
every  feature,  and  for  eliminating  all  forms  of  error,  rt  is 
provided  with  a  finely-graduated  horizontal  circle,  a  vertical 
micrometer  screw,  having  a  graduated  head ;  a  fine  reversible 
spirit-level,  and  a  telescope  of  the  most  accurate  optical  and 
mechanical  construction. 


QUEEN"  ENGINEERS'  LEVEL. 


Price,  $110.00. 


THE  ADJUSTMENTS 

OF   THE 

ENGINEERS'  LEVEL. 

THE  adjustments  of  an  engineers'  level  may  be  conven- 
iently treated  of  under  two  heads:  (i)  The  maker's 
adjustments,  or  those  which  the  scientific  maker  gives  the 
instrument  in  the  course  of  its  construction  and  testing ;  and 
(2)  The  field  adjustments,  or  those  which  require  occasional 
verification  by  the  engineer. 

THE  SIAKER'S  ADJUSTMENTS. 

It  is  necessary  that  the  following  conditions  be  realized  in 
the  construction  and  adjustment  of  a  good  level  : 

(1)  The  lenses  of  the  objective  and  of  the  eye-piece  of  the 
telescope  truly  centred  in  their  respective  cells. 

(2)  The  optical  axis  of  the  system  of  lenses  coinciding  with 
the  mechanical  axis  of  the  tube,  in  all  the  relative  positions  of 
the  objective  and  eye-piece,  the  lenses'  remaining  always  at 
right  angles  to  this  axis. 

(3)  The  cross-hairs,  during  each  observation  in  the  common 
focus  of  the  object-glass  and  eye-piece. 

(4)  The  cross- hairs  truly  centred  with  respect  to  the  me- 
chanical axis  of  the  telescope. 

(5)  The   collars    truly   circular   and   of  exactly  the    same 
diameter. 

(6)  The  wyes  of  exactly  equal  shape. 

(7)  The  horizontal  cross-hair  (all  other  adjustments  made) 
at  right  angles  to  the  vertical  axis  of  the  instrument,  and  the 
vertical  one  vertical. 

(8)  The  line  of  sight  at  right  angles  to  the  vertical  axis  of 
the  instrument,  or  coinciding  with  the  axis  of  collimation. 

(9)  The  axis  of  the  telescope  level  lying  in  the  same  plane 
as  the  line  of  collimation,  or  not  "  crossed  "  with  respect  to  it. 

123 


124  ENGINEERS'  LEVEL. 

(10)  The  axis  of  the  telescope  level  parallel  with  the  line 
of  sight. 

(11)  The  telescope  level  of  a  sensitiveness  corresponding  to 
the  magnifying  power  of  the  telescope. 

(12)  The  telescope  level  of  equal  sensitiveness  throughout 
its  entire  scale. 

(13)  The  axis  of  the  accessory  levels,  attached  to  the  level- 
ing head,  at  right  angles  to  the  vertical  axis  of  the  instrument. 

This  list  is  to  be  taken  as  but  fairly  representing  the  princi- 
pal adjustments  to  be  accomplished  by  the  maker.  It  is  not 
intended  to  be  absolutely  exhaustive. 

THE    FIELD    ADJUSTMENTS. 

The  following  practical  methods  for  detecting  and  correct- 
ing the  errors  of  adjustment  of  the  Engineers'  Level  are  given 
for  use  in  the  field.  An  explanation  of  the  nature  of  each 
error  is  incidentally  embodied. 

There  are  but  two  principal  adjustments  to  be  verified  by 
the  engineer,  viz. :  that 

I.  The  sight-axis  of  the  telescope  and  the  axis  of  the  tele- 
scope level  parallel. 

II.  The  axis  of  the  .telescope  level  at  right  angles  to  the 
vertical  axis  of  the  instrument. 

All  other  adjustments  are  subsidiary  and  accessory  to  these, 
and  will  be  explained  in  their  proper  places.  The  sequence 
of  these  adjustments  is,  as  here  stated,  in  the  case  of  any  ad- 
justable wye  level,  like  the  Engineer's  or  Precision  Level. 
The  Dumpy  Level,  however,  requires  the  converse  order,  as 
hereafter  explained. 

First  Adjustment : —  To  make  the  line  of  sight  parallel  to  the 
axis  of  the  telescope  level, 

This  adjustment  may  be  performed  by  two  methods,  each 
of  which  commends  itself,  under  different  circumstances.  The 
first  is  called  the  Instrumental  Method,  because  it  depends 
only  on  manipulation  of  the  instrument  itself;  the  second, 
requiring  also  readings  on  the  leveling  rod,  is  called  the  Rod 
Method. 


THE    Anjl'STMKNrs     (>F    TIIK  125 

I.  The  Instrumental  Method  divides  this  adjustment  into  the 
two  operations,  (a)  of  bringing  the  line  of  sight  into  the  geometri- 
cal axis  of  the  rings  or  collars,  and  (/))  of  making  the  axis  of 
the  telescope  level  parallel  to  the  bottoms  of  the  collars.  As- 
suming that  the  rings  are  of  exactly  the  same  diameter,  this 
indirect  method  of  making  the  sight-axis  and  the  level-axis 
parallel  to  the  line  joining  the  bottoms  of  the  collars  brings 
these  axes  parallel  to  each  other.  We  may  now  briefly  ana- 
lyze each  of  these  sub-adjustments. 

(a)  To  bring  the  line  of  sight  into  tlie  geometrical  axis  of  tJic 
rings. 

DETECTION  OF  THE  ERROR  : — Direct  the  telescope  to  as 
distant  an  object  as  may  still  be  clearly  defined.  After  loosen- 
ing the  wye  clips,  carefully  rotate  the  telescope  upon  the  wyes 
and  note  whether  the  intersection  of  the  cross-hairs  remains 
on  a  given  stationary  point  of  the  image.  If  the  wires  appear 
to  move  with  respect  to  the  image,  the  line  of  sight  is  not  in 
the  axis  of  the  rings.  The  line  of  sight  being  determined  by 
the  optical  centre  of  the  objective  and  the  point  of  intersection 
of  the  cross-hairs,  both  points  should  be  brought  into  the  axis 
of  the  rings,  and  in  all  conditions  of  use  of  the  telescope  re- 
main there.  For  a  description  of  the  centering  of  the  tele- 
scope, the  reader  is  referred  to  the  article  of  this  Manual 
entitled  "  The  Telescopes  of  Engineering  Instruments"  It  is 
now,  in  the  first  place,  assumed  that  the  optical  centre  of  the 
objective  is  in  the  axis  when  the  objective  is  in  position  for 
viewing  a  distant  object.  In  the  second  place,  the  deviation 
of  the  line  of  sight  during  rotation  of  the  telescope  on  the 
wyes  is,  therefore,  due  to  the  eccentric  position  of  the  intersec- 
tion of  the  cross-hairs. 

CORRECTION  OF  THE  ERROR  : — Giving  attention  to  each  wire 
in  turn,  note  the  position  of  the  rotated  telescope,  which  gives 
the  maximum  deviation  of  the  wire  from  the  selected  point  of 
the  image.  Then  by  means  of  the  proper  set  of  capstan- 
headed  screws  of  the  cross-hair  ring,  bring  each  wire  in  turn 
half  way  back  toward  the  point  of  .the  image.  Repeat  until 
the  centre  of  the  cross-hairs  remains  accurately  bisecting  a 


126  ENGINEERS'  LEVEL. 

point  of  the  image  during  a  complete  revolution  of  the  tele- 
scope on  the  wyes. 

The  centering  of  the  objective  slide  is  an  accessory  adjust- 
ment, and  may  be  undertaken  after  the  centering  of  the  cross- 
hairs has  been  effected  by  the  preceding  method.  It  is  only 
necessary  to  focus  on  a  very  near  object  by  means  of  the  slide, 
and  then  rotating  the  telescope  in  its  wyes  as  before,  correct 
half  the  deviation  of  each  thread  in  turn  by  means  of  the  slide- 
centering  screws.  See  also  the  article  on  "  The  Telescopes  of 
Engineering  Instruments"  already  mentioned. 

(b)  To  make  the  axis  of  the  telescope-level  parallel  to  the  bot- 
toms of  the  rings. 

DETECTION  OF  THE  ERROR  : — Clamp  the  axis  of  the  instru- 
ment, and  carefully  level,  particularly  with  the  pair  of  leveling 
screws  lying  parallel  to  the  telescope.  Now  gently  reverse 
the  telescope  end  for  end  in  the  wyes,  and  note  whether  the 
bubble  returns  to  the  same  central  reading.  If  the  bubble 
deviates  from  its  original  position,  this  deviation  is  double  the 
error. 

CORRECTION  OF  THE  ERROR  : — Correct  one-half  of  the  de- 
viation observed  on  reversal  in  the  wyes  by  means  of  the  ver- 
tical adjusting  screws  of  the  level-tube.  Level  again,  and,  as 
a  check,  repeat  the  operation. 

The  crosswise  position  of  the  level,  or  the  condition  in  which 
the  level  axis  is  not  in  the  same  vertical  plane  with  the  line  of 
sight,  is  to  be  carefully  avoided  in  connection  with  all  adjust- 
ments and  uses  of  the  level.  After  every  adjustment  of  the 
level-tube,  careful  examination  should  be  made  for  the  cross- 
ing. This  condition  is  tested  for  by  turning  the  telescope 
slightly  on  the  wyes  and  noting  whether  the  bubble  still  coA- 
tinues  to  remain  central.  If  not,  adjust  by  means  of  the  lateral 
adjusting  screws  of  the  level-tube  until,  on  rocking  to  and  fro 
on  the  wyes,  the  bubble  remains  stationary.  Compare  the 
paragraph  on  "  the  crosswise  position  of  the  level  "  in  the  arti- 
cle of  this  Manual  entitled  "  The  Spirit-levels  of  Engineering 
Instruments."  The  importance  of  this  adjustment  lies  in  the 
fact  that  the  error  of  crossing  of  the  level  may  produce  quite 


THE    ADJl'STMKNTS     OF     THE  127 

a  material  divergence  of  the  line  of  sight  from  the  horizontal 
direction,  if  the  telescope  happens  to  be  turned  slightly  round 
in  the  wyes,  oc  if  the  instrument  is  not  accurately  leveled  in 
the  direction  perpendicular  to  the  line  of  sight. 

When,  as  in  the  Dumpy  Level  and  in  the  Engineers' 
Transit,  the  telescope  does  not  revolve  in  wyes  about  the  line 
of  sight,  the  following  method,  due  to  Helmert,  may  be  used 
to  detect  and  adjust  for  the  crosswise  position  of  the  level 
axis.  All  other  adjustments  accurately  made,  set  up  the  in- 
strument with  the  line  of  sight  parallel  to  two  leveling  screws, 
and  direct  it  to  a  rod  placed  at  a  distance  of  several  hundred 
teet.  Then,  by  means  of  the  other  set  of  leveling  screws, 
slightly  rotate  the  telescope  about  the  line  of  the  parallel  set, 
at  the  same  time  that,  by  means  of  the  parallel  set,  the  level 
is  kept  to  zero  reading.  The  deviation  of  the  line  of  sight  thus 
caused  and  read  off  on  the  rod,  will  be  a  measure  of  the  cross- 
ing error,  provided  allowance  is  made  for  the  very  small  varia- 
tion in  the  height  of  the  line  of  sight.  The  adjustment  for  the 
crossing  is  to  be  effected  by  means  of  the  lateral  adjusting 
screws  of  the  level. 

The  inequality  in  diameter  of  the  rings  may  be  found  by 
means  of  a  striding  level  which  is  read  both  in  the  direct  and 
reversed  positions  on  the  rings,  for  each  of  the  two  positions 
of  the  telescope  in  the  wyes,  direct  and  reversed.  The  bubble 
movement,  due  alone  to  reversal  of  the  telescope  in  the  wyes, 
measures  twice  the  inequality  of  the  rings  ;  but  the  inequality, 
or  angle  at  the  apex  of  the  arc  formed,  is  also  twice  the  angle 
made  by  the  axis  of  the  rings  with  the  edge.  Therefore,  one- 
fourth  of  the  bubble  movement,  due  to  reversal  of  telescope, 
equals  the  inequality  of  rings  expressed  in  bubble  divisions. 
This,  multiplied  by  the  angular  value  of  a  division  of  the  level, 
gives  the  angular  value  of  the  inequality. 

If  the  instrument  is  properly  made,  the  rings  are  so  nearly 
of  equal  diameter  that  the  assumption  of  equality  required  in 
the  foregoing  adjustment  leads  to  errors  quite  inappreciable 
except  in  the  highest  class  of  work. 

II,  The  Rod  Method  requires  the  use  both  of  the  instrument' 


128 


ENGINEERS      LEVEL. 


and  of  the  leveling  rod.  and  is  frequently  spoken  of  as  the  "  peg 
adjustment."  It  has,  in  one  form,  been  already  described  un- 
der the  head  of  the  "  Fourth  Adjustment"  of  the  Engineers' 
Transit,  and,  as  there  given,  is  also  applicable  to  the  Engi- 
neers' Level.  The  rod  method,  being  a  direct  one,  and  inde- 
pendent of  the  diameter  of  the  rings,  is  of  great  practical  im- 
portance, and  is  therefore  here  given  in  another  form. 

DETECTION  OF  THE  ERROR  : — Drive  two  stakes,  several  hun- 
dred feet  apart,  on  nearly  level  ground.  Set  up  the  instrument 
successively  in  two  symmetrical  positions,  as,  Fig.  52,  either  in 
/  and  /,  or  in  K  and  L,  and  near  the  rods.  If  we  suppose  the 
positions  to  be  /  and  Jy  the  eye-hole  is  to  be  brought  very 
near  the  rod  in  setting  up,  and  the  height  of  the  eye-end  may 
then  be  found  by  looking  through  the  objective,  and  with  a 
sharp  pencil  point  marking  the  centre  of  the  small  field  upon 
the  rod.  If  the  positions  used  are  K  and  Z,  the  readings  on 
the  rods  near  by  are  made  through  the  telescope  by  moving 
out  the  focusing  slide  far  enough  to  secure  distinct  vision. 


L    BJ  A 

Fig-  52. 

Letting  el  equal  the  reading  on  the  near  rod  for  the  instru- 
mental position  either  in  /or  in  K,  o^  the  reading  on  the  dis- 
tant rod  for  the  sam£  position,  c\2  the  reading  on  the  near  r£>d 
for  the  instrumental  position  either  in  /or  in  Z,  o.2  the  reading 
on  the  distant  rod  for  the  same  position,  -|-/the  elevation  of 
A  above  B,  and  -\-d  the  upward  deviations,  as  measured  on 
the  distant  rod,  of  the  line  of  sight  from  the  axis  of  the  level, 
we  have  the  evident  relations  — 


(2) 


THE    ADJUSTMENTS     OF    THE  1  29 

Whence,   by   simple   elimination    in   (i)    and   (2),  we   easily 
find  the  following  : 

%  (*!+**)  —  j£('i  +  '2)=*  (3) 

y2  (Oi  _  ^2)_  y2  (V_  c,2)=  /  (4) 

Also  from  equation  (2)  we  have  — 

o2—d  =  e.2—l  (5) 

Equation  (3)  gives  the  upward  deviation  d,  which,  applied  in 
(2),  would  give  /.  It  is,  however,  convenient  to  use  (4)  to  find 
/,  and  then  use  (5)  as  a  check  on  the  work. 

Example  — 

^—5.428  ft.  ^=5.122  ft. 

^2=5-175  "  *2= 


Halfsums,  5.3015  5-2955 

Half  differences,  0.1265  —0.1735 

Whence  d=o.oo6        and       /=o.3OO 
Also,  o2  —  ^=5.169   and    e2  —  7=1:5.169 

CORRECTION  OF  THE  ERROR  :  —  With  the  instrument  remain- 
ing in  the  last  position  —  namely,  either  in  J  or  in  L  —  rset  the 
target  of  the  distant  rod  to  the  reading  <?2  —  d,  remembering 
that  -\-d  is  an  upward,  and  —  d  a  downward  deviation  of  the 
line  of  sight,  and  that,  hence,  d  for  an  upward  deviation  is  sub- 
tractive  from  the  last  distant  rod  reading,  and,  for  a  downward 
reading,  additive  to  it.  Now,  taking  care  to  keep  the  level- 
bubble  at  zero  reading,  adjust  the  horizontal  cross  wires,  by 
means  of  the  set  of  capstan-headed  screws  at  right  angles  to 
it,  until  the  wire  intersects  the  adjusted  target  of  the  distant 
rod.  The  line  of  sight  is  then  parallel  to  the  axis  of  the  level. 

Second  Adjustment:  —  To  bring  the  axis  of  the  telescope  level 
at  right  angles  to  the  vertical  axis  of  the  instrument. 

This  adjustment  is  intended  to  obviate  the  necessity  of  re- 
leveling  the  instrument  upon  revolving-  the  telescope  horizont- 
ally. 

DETECTION  OF  THE  ERROR  :  —  Carefully  level  the  instrument. 
Revolve  on  the  vertical  axis  1  80°  and  re-read  the  level.  The 
bubble  deviation  will  be  equal  to  double  the  error. 


130  ENGINEERS      LEVEL. 

CORRECTION  OF  THE  ERROR  : — Correct  half  of  the  bubble 
deviation  by  means  of  the  screws  at  the  end  of  the  level-bar 
which  vertically  adjust  the  wye.  Then  level  by  means  of  the 
leveling  screws,  and  repeat  the  observation  as  a  check. 

The  Adjustments  of  the  Dumpy  Level  are  the  same  two  already 
•described  in  this  article.  But  owing  to  the  telescope  being 
immovably  attached  to  the  level-bar,  they  must  be  performed 
in  the  inverse  order.  The  parallelism  between  the  sight-axis 
and  the  level  axis  can,  indeed,  be  secured  either  by  means  of 
the  vertical  adjusting  screws  of  the  level  tube,  or  by  means  of  the 
adjusting  screws  of  the  cross-wires.  But  since  the  level  axis  is 
.also  to  be  at  right  angles  to  the  vertical  axis  of  the  instru- 
ment, this  adjustment  of  the  level  is  first  secured,  and  then  the 
line  of  sight  rendered  parallel  to  the  level-axis  by  means  of  the 
cross-hair  adjusting  screws,  according  to  the  rod  methods  of 
adjustment  described  in  this  article,  and  under  the  "  Fourth 
Adjustment"  of  the  Engineers'  Transit. 

The  Second  Adjustment  of  this  article  must  then  be  per- 
formed, first,  by  carefully  leveling,  revolving  the  whole  instru- 
ment horizontally  180°,  and  correcting  one-half  the  bubble 
deviation  by  means  of  the  vertical  adjusting  screws  of  the 
level-tube.  The  First  Adjustment  of  this  article  is  then  per- 
formed by  some  form  of  the  Rod  Method.  Here  the  final  re- 
sult is  to  determine  a  rod  reading  for  a  horizontal  position  of 
the  line  of  sight,  and  hence  enable  the  cross-hairs  to  be 
brought  to  that  reading  when  the  level  is  at  the  zero  reading. 

Queen  &  Co.,  realizing  the  advantage  which  accrues  to  the 
engineer  from  the  use  of  a  Level  adjusted  in  every  part  with 
thorough  accuracy,  pay  special  attention  to  each  detail  con- 
ducive to  this  result.  Whatever  adds  to  the  permanencyW 
the  adjustments  is  considered  essential,  and  each  instrument 
sent  out  is  first  subjected  to  a  complete  and  accurate  adjust- 
ment. 


LENGTH  MEASUREMENT 


IN 


ENGINEERING. 


ONE  of  the  most  important  practical  operations  to  be  per- 
formed by  the  engineer  is  the  measurement  of  length. 
The  true  theory  of  such  measurement,  and  the  best 
means  of  attaining  the  degree  of  accuracy  proper  to  each  kind 
of  work,  should  therefore  be  familiar.  And  yet,  owing  to  the 
frequent  laxity  of  opinion  existing  on  this  subject,  we  would 
offer  no  apology  for  making  a  brief  review  of  the  matter  here. 

It  is  not  necessary  to  remind  the  capable  engineer  that  one 
of  the  most  weighty  considerations  in  his  work  is  the  degree 
of  error  alloivable,  profitable,  or  unavoidable  in  each  given  case, 
with  the  given  appliances.  It  is  only  the  young  and  untrained 
engineer  who  would,  for  instance,  take  a  measuring  unit  pos- 
sessing an  unknown  error  probably  as  great  as  I  in  1 ,000,  and 
then  by  much  expenditure  of  time  and  labor  in  the  actual 
measurement,  endeavor  to  reduce  the  latter's  error  to  I  in 
10.000. 

There  should  exist  a  proper  proportionality  of  error  between 
the  various  kinds  of  measurements,  as  of  length,  angle,  and 
time,  made  by  the  engineer  in  any  given  work.  For  a  sur- 
veyor usin^  a  compass  giving  bearings  to  quarters  of  a  degree 
it  would  be  as  absurd  to  think  of  measuring  the  lines  run  by 
means  of  a  base-line  apparatus,  such  as  used  in  refined  geo- 
detic work,  as  it  would  for  the  geodetic  engineer,  measuring 
the  angles  of  his  triangles  to  within  a  few  seconds,  to  contem- 
plate using  an  old-fashioned  surveyor's  chain  on  his  base- 
lines. 

It  is,  however,  of  the  highest  importance  always  to  use  the 
most  nearly  accurate  unit  of  length  measurement  which  the 


132  LENGTH    MEASUREMENT 

class  of  work  will  warrant.  And  this,  for  the  reason  that  the 
original  errdr  of  length  in  chain,  tape,  or  bar  used  will  accumu- . 
late  to  serious  proportions  when  a  long  line  is  measured.  The 
fact  that  in  his  work  such  errors  always  enter  with  the  same 
sign  and  hence  are  cumulative  in  character  should  be  sufficient 
caution  to  the  engineer  against  introducing  a  constant  error 
by  the  choice  of  an  uncertain  unit  of  length  measurement. 

There  are,  on  the  other  hand,  purely  accidental  errors  of 
length  measurement,  which,  as  the  theory  of  probabilities 
informs  us,  are  largely  compensated  by  each  other.  Such 
errors  are  those  arising  from  setting  the  pins  or  marking  the 
lengths.  At  first  view  one  should  think  that  these  errors 
would  far  outweigh  any  moderate  constant  errors  of  the  chain 
or  tape.  But  such  an  illusion  can  readily  be  dispelled  by  con- 
sidering a  practical  case.  When,  for  instance,  a  mile's  length  is 
measured  by  means  of  a  chain  66  feet  long,  the  very  process  of 
end  to  end  measurement  gives  in  effect  a  mean  or  average  length 
to  the,  chain,  similar  to  that  which  would  be  derived  by  meas- 
uring the  length  of  the  chain  itself  80  times  (80X66—5280), 
and  taking  the  mean.  Let  us  suppose  the  "•  mean  error  "  e 
of  a  single  measurement  to  be  0.4  inch.  Then,  if  m  equals 
the  number  of  measurements  and  R  the  probable  error  of  their 
sum,  we  have  from  the  Method  of  Least  Squares  : 

R=.  6745.8.  j/  m 
or  for  our  case,  approximately : 

7?— 2^X4X9=2.4  inches. 


That  is,  the  most  probable  total  error  in  the  mile  arising  from 
marking  the  lengths,  would  be  2.4  inches. 

But  if,  on  the  other  hand,  the  chain  used  had  been  0.2  inch 
too  long  or  too  short,  80  measurements  would  have  increased 
this  error  to  a  total  of  16  inches.  In  other  words,  the  final 
error,  so  far  as  it  depends  on  the  unavoidable  inaccuracy  of 
marking  the  lengths,  is  proportional  to  but  the  square  root  of 
the  number  of  measurements,  whereas,  so  far  as  it  depends  on 
the  faulty  unit,  it  is  directly  proportional  to  the  number  of 
measurements.  It  is  therefore  plain  that  a  constant  error  in 


IX    ENGINEERING.  I^$ 

the  unit  of  measurement  employed  is  of  much  more  serious 
consequence  than  thejHtrtfy  accidental  errors  which  accompany 
a  careful  use  of  the  unit. 

Realizing  the  necessity  for  accuracy  in  the  units  of  length 
measurements  used  by  the  engineer  and  comprehending  the 
public  appreciation  of  all  that  advances  the  character  and 
standard  of  engineering  work,  QUEEN  &  Co.  have  brought  all 
the  resources  of  their  relations  with  men  of  science  and  ex- 
pert mechanicians  in  this  country  and  abroad,  to  bear  upon  the 
practical  solution  of  the  problem. 


DESCRIPTION 

OF   THE 

PLANE    TABLE. 


THE  plane  table  is   a  well-made  and  properly  mounted 
drawing-board  carrying  on  it  an  alidade  provided  with 
a  telescopic  line  of  sight  and  a  ruler  of  fiducial  edge. 
Its  purpose  is  to  enable  angles  to  be  transferred  from  nature 
to  a  sheet  of  paper  attached  to  the  drawing-board. 

The  Tripod  and  Head  are  usually  larger  and  heavier  than 
those  used  with  the  ordinary  transit.  The  tripod  head  is  of 
the  usual  type,  and  may  be  of  the  shifting  sort,  so  as  to  allow. 
a  slight  lateral  motion. 

The  metallic  plate,  which  is  fastened  to  the  table,  has  pro- 
jecting from  its  centre  a  finely-turned  conical  spindle,  and 
there  is  added  the  usual  clamp  and  tangent  motion.  In  all  of 
the  QUEEN  &  Co.  types  of  the  plane  table  the  head  is  made 
large  enough  to  afford  a  perfectly  firm  bearing  service. 

The  Drawing  Board  is  of  rectangular  shape,  usually  24x30 
inches,  and  is  made  of  well-seasoned  wo'od  so  joined  together 
as  to  obviate  warping,  and  is  provided  with  spring  clamps  for 
keeping  the  paper  properly  stretched.  The  board  is  also 
provided  with  suitable  levels. 

The  Plumbing  Arm  has  a  sharp  point  at  one  end  and  a 
plummet  suspended  from  the  other,  and  enables  any  point  on 
the  ground  to  be  transferred  to  its  proper  position  on  t|e 
board. 

The  Declinator  consists  of  a  rectangular  compass-box  pro- 
vided with  carefully  wrought  edges  whose  directions  coincide 
with  the  lines  conceived  as  passing  through  the  zero  points 
of  the  graduated  circle  of  the  compass.  By  means  of  it  the 
table  may  be  oriented,  or  lines  drawn  on  the  board  parallel  to 
any  given  line  on  the  ground. 
134 


THE    PLANE    TABLE.  ^5 

The  Alidade  consists  essentially  of  a  metallic  straight-edge 
about  22  inches  long  and  2  inches  wide,  to  which,  at  its  cen- 
tre, is  attached  a  column  carrying  the  telescope.  The  alidade 
has  attached  to  it  either  one  round  or  two  cross-levels  ad- 
justed with  respect  to  the  lower  surface  of  the  ruler,  and  of 
use  in  leveling  the  table.  In  the  best  form  of  alidade  a  level- 
is  placed  at  right  angles  to  the  line  of  sight,  and  the  horizontal 
axis  of  the  telescope  may  by  means  of  this  level  and  a  suitable 
adjusting  screw  be  kept  horizontal  independently  of  the  lev- 
eling of  the  table. 

The  Telescope  has  no  lateral  motion  with  respect  to  the 
straight-edge,  being  rigidly  connected  with  it,  and  with  it  may 
be  moved  to  any  part  of  the  table.  The  telescope  is,  however, 
capable  of  a  vertical  motion  on  a  transverse  axis  which  car- 
ries a  graduated  arc  with  clamp  and  tangent  motion,  and  so 
permits  the  small  vertical  angles  to  be  read  off.  The  tele- 
scope has  attached  to  it  a  level  whose  plane  is  adjustable  to  a 
position  parallel  to  the  line  of  sight.  A  striding  level  is  also 
sometimes  provided  for  the  transverse  axis  of  the  telescope. 
Stadia  wires  are,  on  account  of  their  convenience  in  measuring 
distances,  always  inserted. 

If  the  level  is  attached  parallel  to  the  line  of  sight  of  the 
telescope  two  readings  are  required  for  a  vertical  angle,  one 
for  the  direction  of  the  point  and  one  for  the  horizontal  direc- 
tion. If,  however,  the  level  is  attached  to  the  vernier  arm  of 
the  vertical  arc,  one  reading  of  the  circle  after  the  bubble  is 
brought  to  zero  suffices  to  give  the  vertical  elevation  of  the 
point. 

The  Forms  of  the  Plane  Table  furnished  by  QUEEN  &  Co. 
vary  according  to  the  grade  of  work  for  which  they  are  in- 
tended. The  chief  differences  lie  in  the  size  of  the  table,  the 
size  and  power  of  the  telescope,  the  sensitiveness  and  positions 
of  the  levels  furnished,  and  the  accessory  conveniences  at- 
tached. Of  all  these,  a  full  description  is  given  in  QUEEN 
&  Co.'s  catalogue. 


THE  ADJUSTMENTS' 

OF   THE 

PLANE  TABLE. 


THE  adjustments  of  the  plane  table  may  be  conveniently 
stated  under  two  heads  :  (i)  The  maker's  adjustment 
are  those  which  the  scientific  maker  gives  the  instru- 
ment during  its  construction  and  testing,  and  (2)  The  field 
adjustments  are  those  which   have  occasionally  to  be  verified 
by  the  engineer. 

THE  MAKER'S  ADJUSTMENTS. 

It  is  necessary  that  the  following  conditions  be  met  in  the 
construction  and  adjustment  of  a  good  plane4 table  : 

1.  The  upper   surface  of   the  table  or  drawing-board,  as 
nearly  as  possible,  a  true  mathematical  plane. 

2.  The  vertical  axis    of    the  table  at  right  angles  to  the 
plane  of  the  board. 

3.  The  feather  edge  of  the  ruler  a  mathematically  straight 
line. 

4.  The  plane  of  the  plate-levels  parallel  to  the  lower  sur- 
face of  the  alidade  ruler. 

5.  The  lenses  of  the  objective  and  of  the  eye-piece  of  the 
telescope  truly  centered  in  their  respective  cells. 

6.  The  optical  axis  of  the  telescopic  system  of  lenses  coin- 
ciding with  the  mechanical  axis  of  the  tube  in  all  the  relative 
positions  of  objective  and  eye-piece  at  the  same  time  that  the 
lenses  always  remain  at  right  angles  to  this  axis. 

7.  The  stadia  and  cross  wires,  during  an  observation,  in  the 
common  focus  of  the  object-glass  and  the  eye-piece. 

8.  The  vertical  cross-hair  at  right  angles  to  the  horizontal 
axis  of  the  telescope,  and  the  horizontal  cross-hair  accurately 
at  right  angles  to  the  former. 

136 


"QUEEN"  PLANE  TABLE. 


A  1522. 


Price,  $200 


THE    PLANE    TABLE. 


137 


9.  The  line  of  sight  at  right  angles  to  the  horizontal  axis  of 
the  telescope  or  coinciding  with  the  axis  of  collimation. 

10.  The  axis  of  the  telescope-level  lying  in  the  same  plane 
as  the  line  of  sight,  or  not  "  crossed  "  with  respect  to  it. 

1 1.  The  axis  of  the  telescope-level  parallel  with  the  line  of 
sight. 

1 2.  The  axis  of  the  level  attached  to  the  vernier  arm  of  the 
vertical  arc  horizontal  when  the  vernier  reads  zero. 

13.  The  horizontal  axis  at  right  angles  to  the  vertical  axis 
of  the  table,  and  hence  parallel  to  the  plane  of  the  table. 

14.  The  plane  of  the  vertical  arc  parallel  to  the  vertical  axis 
of  the  instrument. 

15.  The  vertical  arc  without  appreciable  errors  of  gradua- 
tion or  of  eccentricity. 

1 6.  The  vernier  of  the  vertical  arc  reading  zero  either  when 
the  level  attached  to  its  arm  reads  zero,  or  when  the  telescope 
reads  zero  and  the  line  of  sight  is  horizontal. 

This  list,  while  not  exhaustive,  will  serve  to  direct  the  atten- 
tion of  the  engineer  to  some  of  the  more  essential  requisites 
of  a  well-constructed  instrument. 

THE    FIELD    ADJUSTMENTS. 

The  following  practical  methods  for  detecting  and  cor- 
recting the  errors  of  adjustment  of  the  plane  table  are  given 
for  use  in  the  field. 

They  are  so  similar  to  those  stated  under  the  head  of  the 
Engineer's  Transit  and  the  Engineer's  Level  as  to  require 
but  little  further  explanation. 

The  principal  conditions  are : 

1.  That  the  plane  of  the  table  shall  be  approximately  hori- 
zontal during  use. 

2.  That  the  feather  edge  of  the  ruler  shall,  under  all  con- 
ditions, if  it  does  not  coincide  or  is  not  parallel  with  the  pro- 
jection on  the  table  of  the  line  of  sight  of  the  telescope,  at 
any  rate  make  a  constant  angle  with  it. 

3.  That  the  horizontal  axis  of  the  telescope  shall  be  truly 
horizontal  during  a  pointing  at  some  altitude. 


138  THE    PLANE    TABLE. 

First  Adjustment:  —  To  make  the  axes  of  the  plate  levels  par- 
allel to  the  plane  of  the  table, 

DETECTION  OF  THE  ERROR  :— With  the  alidade  placed  in 
any  marked  position,  carefully  level  the  table  and  note  the 
readings  of  the  levels.  Now  delicately  lift  the  alidade  from 
the  table  and  replace  it,  when  reversed,  in  exactly  the  same 
position  on  the  board. 

The  consequent  displacement  of  the  bubbles  will  be  twice 
the  error  of  adjustment  of  the  bubble  tubes. 

CORRECTION  OF  THE  ERROR  : — Bring  the  bubbles  half-way 
back  to  the  centres  of  the  tubes  by  raising  or  lowering  either 
end  of  the  tubes  by  means  of  the  adjusting  screws.  Then 
accurately  level  the  table  by  means  of  the  plate  screws  and 
repeat  the  operation. 

Sesond  Adjustment: — To  make  the  line  of  sight  coincide  with 
the  line  of  collimation,  or  to  make  the  line  of  s'ght  perpendicular 
to  the  horizontal  axis  of  the  telescope. 

This  adjustment  is  absolutely  essential  in  instruments  where 
the  telescope  of  the  alidade  may  be  transited.  It  is  made  in 
the  manner  already  described  in  the  article  of  this  Manual  on 
the  adjustments  of  the  Transit.  In  case  the  telescope  does  not 
transit,  it  may  be  reversed  by  lifting  it  from  its  horizontal  bearings. 

In  this  connection  it  should  be  clearly  understood  that  it  is 
not  necessary  that  the  projected  line  of  sight  should  coincide 
or  be  parallel  with  the  fiducial  edge  of  the  ruler.  It  may 
make  any  small  constant  angle,  since  this  only  occasions  a 
constant  difference  of  direction  of  lines  on  the  table  as  com- 
pared with  the  lines  on  the  ground,  and  this  displacement  of 
the  drawing  is  of  no  consequence  on  removal  of  the  drawing 
from  the  table. 

Third  Adjustment : — To  make  the  line  of  collimation  revolve 
in  a  vertical  plane. 

The  detection  and  correction  of  this  error  are  the  same  as 
in  the  case  of  the  third  adjustment  of  the  transit  instrument. 

Instead,  however,  of  doing  this  adjustment  elaborately,  it 
will  usually  suffice  to  level  the  table;  sight  to  a  long  plumb- 


THE    PLANE    TABLE.  j-g 

line,  and  note  whether  in  moving  the  telescope  through  a  ver- 
tical arc  the  cross-threads  continually  bisect  the  line ;  and  if 
they  do  not,  raise  or  lower  one  end  of  the  transverse  axis 
until  this  is  accomplished. 

Fourth  Adjustment: — To  make  the  axis  of  the  telescope-level 
parallel  to  t/ie  line  of  sigJit. 

This  adjustment  may  be  tested  by  one  of  the  peg-adjustment 
methods  described  in  treating  the  adjustments  of  the  transit 
and  the  level. 

Fifth  Adjustment: — To  make  the  vertical  arc  read  zero  when 
the  telescope-level  reads  zero. 

This  adjustment  assumes  that  when  the  level  reads  zero, 
the  line  of  sight  is  horizontal.  The  error  may  be  noted  by 
simple  inspection,  and  if  the  vernier  cannot  be  accurately  ad- 
justed to  a  zero  reading,  it  is  convenient  to  record  the  index 
error  and  apply  this  to  readings  of  vertical  angles. 

Sixth  Adjustment: — To  test  the  truth  of  the  fiducial  edge  of 
the  ruler. 

Draw  a  fine  line  along  the  edge  of  the  ruler  and  then  re- 
verse the  alidade  and  replace  upon  the  line.  If,  now  moving 
the  alidade  along  in  the  direction  of  the  line,  it  coincides  at 
every  point,  the  edge  is  mathematically  straight.  If  not,  it 
will  be  necessary  to  have  it  ground  straight  by  the  maker. 

QUEEN  &  Co.  deem  it  important  to  examine  carefully  and 
verify  every  adjustment  before  sending  out  an  instrument;  and, 
with  careful  usage,  the  adjustments  of  the  Plane  Table  should 
require  very  little  attention  on  the  part  of  the  engineer.  • 


THE  SOLAR  TRANSIT 

AND   ITS   METHOD   OF  DETERMINING 

THE  ASTRONOMICAL  MERIDIAN, 


THE  Solar  Attachment  as  shown  in  the  accompanying  cut 
consists  of  a  small  telescope  mounted  on  a  horizontal 
axis,  which  rests  upon  two  standards  connected  to  a 
circular  base.  This  base  is  the  socket  of  the  so-called  polar 
axis,  and  is  attachable  at  its  lower  extremity  to  the  horizontal 
axis  of  the  telescope.  The  solar  telescope  is  thus  capable  of 
being  turned  on  its  own  horizontal  axis  and  on  its  polar  axis. 
A  small  level  is  applied  parallel  to  the  -solar  telescope.  Two 
pointers  are  also  attached  for  use  as  a  species  of  finder,  the 
sun  appearing  in  the  field  of  view  of  the  telescope  when  the 
shadow  of  one  of  these  pointers  is  thrown  on  the  other.  The 
solar  telescope  is  provided  with  a  right-angled  prism  for  con- 
veniently observing  the  sun  when  it  is  at  a  considerable  alti- 
tude. It  is,  of  course,  provided  with  shade  glasses  for  the 
purpose  of  reducing  the  intensity  of  the  solar  rays  trans- 
mitted. The  small  graduated  circle  sometimes  attached  to 
the  polar  axis  enables  the  hour  angle  to  be  read  off.  Clamp 
and  tangent  are  provided  both  for  the  vertical  and  for  the  hour 
angle  movement. 

The  Solar  Compass  is  furnished  with  a  special  polar  axis 
placed  parallel  to  the  plane  of  the  sights  and  adjustable  by 
means  of  a  graduated  arc  to  the  latitude  of  the  observer. 
Attached  to  this  polar  axis  is  an  arm  carrying  an  arc  for  set- 
ting off  the  declination  of  the  sun,  and  the  line  of  collimatioh 
is  determined  by  a  lens  at  one  end  of  the  movable  arm  and 
graduated  lines  on  a  silver  plate  at  the  other  end. 

The  solar  compass  may  be  considered  to  have  been  dis- 
placed by  the  addition  of  the  solar  attachment  to  the  engineer's 
transit.  If,  however,  any  one  should  still  prefer  to  work  witli 
a  solar  compass,  its  construction  and  use  may  readily  be  com- 
prehended by  one  who  has  mastered  the  theory  of  the  solar 
140 


THE    SOLAR    TRANSIT.  14! 

transit.     We  therefore  limit  ourselves  to  a  description  of  the 
construction  and  manipulation  of  the  Solar  Transit. 

The  principal  object  of  every  solar  attachment,  whether  it  be 
combined  with  the  compass  to  form  the  solar  compass  or  with 
the  engineer's  transit  to  form  the  solar  transit,  is  to  enable  sur- 

o 

vcyors  to  find  the  direction  of  the  true  or  astronomical  meridian. 

In  every  complete  instrument,  whether  solar  compass  or 
solar  transit,  there  are  two  movements  to  be  accomplished  at 
the  same  time  in  order  to  bring  the  sun's  image  into  the  centre 
of  the  field  of  the  solar  attachment,  and  thus  also  the  line  of 
sight  of  the  instrument  into  the  meridian. 

These  two  movements  are,  first,  one  of  the  solar  attachment 
in  hour  angle,  and  second,  one  of  the  line  of  sight  of  the  in- 
strument itself  in  an  azimuthal  or  horizontal  direction. 

There  are  in  every  instrument  means  for  adjusting  the  in- 
strument to  the  latitude  of  the  place  in  order  that  a  true  polar 
axis  may  be  furnished  on  which  to  rotate  the  attachment  in 
hour  angle,  and  means  also  for  adjusting  the  instrument  to  the 
declination  of  the  sun. 

The  astronomy  necessary  to  an  intelligent  explanation  of  the 
use  of  the  solar  transit  or  of  the  solar  compass  as  means  for  find- 
ing the  true  meridian,  must  now  be  given  in  the  following  brief 
definitions. 

The  line  ZN"  in  the  accompanying  figure  represents  the  di- 
rection of  the  plumb-line  or  vertical  line,  passing  through  the 
eye  of  the  observer  at  O.  Z  is  the  zenith,  N  is  the  nadir. 
Every  plane  passing  through  ZN  is  a  vertical  plane.  The  planes 
ZSB  and  ZEM  are  vertical  planes.  The  horizon  or  plane 
MBL  is  at  right  angles  to  the  plumb-line  or  vertical  line  ZN. 

The  Altitude  of  a  star  vS  is  the  angular  distance  of  the  star 
above  the  horizon  as  measured  on  the  vertical  circle  passing 
through  the  star.  The  altitude  of  5"  is  the  arc  BS.  The  zen- 
itJi  distance  of  a  star  is  the  angular  distance  of  the  star  from  the 
zenith  measured  on  the  vertical  circle  passing  through  the 
star.  The  zenith  distance  of  5  is  ZS.  Altitude  -f-  Zenith  Dis- 
tance =  90°. 

The  Meridian  is  the  vertical  circle  which  passes  through  the 
poles  of  the  heavens,  and  in  the  figure  is  the  circle  MZPLNP '. 

The  Azimuth  of  a  star  is  the  angular  distance  measured  from 


142 


THE    SOLAR    TRANSIT. 


the  south  point  M,  on  the  horizon,  eastward  to  the  vertical 
circle  passing  through  the  star.  The  azimuth  of  the  star  5  is 
the  arc  MB. 

The  Polar  Axis,  PP ,  of  the  celestial  sphere  is  parallel  to  the 
axis  of  the  earth,  and  the  elevation  of  the  north  pole,  P,  above 
the  horizon  is  equal  to  the  latitude  of  the  place.  The  great 
circle  EQ,  at  right  angles  to  the  polar  axis,  represents  the 
celestial  equator. 

The  Hour  Circle  or  Circle  of  Decimation  of  a  star  is  the  great 
circle  which  passes  through  the  star  and  is  at  right  angles  to 
the  equator.  PSDP  is  such  a  circle  of  declination. 

The  Declination  of  a  star  is  the  angular  distance  either  north 


P    Z 


or  south  of  the  celestial  equator  as  measured  on  a  circle  of 
declination  or  hour  circle  of  the  star.  DS  is  the  arc  measuring 
the  north  declination  of  the  star  5*. 

The  Polar  Distance  of  a  star  is  the  complement  of  the  decli- 
nation, and  in  the  figure  is  represented  by  the  arc  PS. 

The  Hour  Angle  of  a  star  is  the  angular  distance  measured 
either  west  or  east  from  the  meridian,  or  the  celestial  equator, 
to  the  circle  of  declination  or  hour  circle  passing  through  the 
star.  ED  is  the  arc  measuring  the  hour  angle  of  the  star  5. 

The  Latitude  of  the  Place  of  Observation  is  represented  in 
the  figure  by  the  arc,  LP,  or  its  equal,  EZ ;  the  co-latitude  v$> 
therefore  equal  to  the  arc  PZ,  or  its  equal,  ME. 


ADJUSTMENT  AND   USE 


OF 


THE   SOLAR   TRANSIT. 


IT  is,  in  the  first  place,  implied  that  all  the  adjustments  01 
the   transit  instrument    heretofore  described  shall  have 
been  accurately  made.     In  addition  to  these  the  two  fol- 
lowing adjustments  are  to  be  accomplished. 

First  Adjustment: — To  bring  the  "polar  axis"  at  right 
angles  to  the  line  of  sight  and  to  the  horizontal  axis  of  the  maiji 
telescope. 

This  may  be  accomplished  by  leveling  the  whole  instrument 
carefully,  and  after  bringing  the  bubble  of  each  telescope-level 
to  its  zero  reading  so  adjust  the  screws  at  the  base  of  the 
44  polar  axis "  that  a  distant  object  may  be  simultaneously 
bisected  in  both  telescopes. 

Another  method  for  accomplishing  the  same  adjustment  is 
to  bring  the  bubble  of  each  telescope-level  central  as  before 
and  then  by  revolving  the  solar  telescope  around  its  polar  axis, 
note  whether  its  bubble  remains  central ;  if  so  the  polar  axis  is 
at  right  angles  to  the  plane  containing  the  line  of  sight  and  the 
horizontal  axis  of  the  main  telescope.  If  the  bubble  of  the 
solar  telescope  in  revolving  about  the  polar  axis  does  not  re- 
main central  correct  half  the  bubble  displacement  by  means  of 
the  adjusting  screws  at  the  base  of  the  polar  axis,  and  the 
other  half  by  revolving  the  solar  telescope  on  its  horizontal 
axis.  Verify  by  repetition. 

The  Second  Adjustment : — To  bring  the  line  of  sight  of  the 
solar  telescope  parallel  to  the  axis  of  its  level. 

This  may  be  effected  by  bringing  both  telescopes  into  the 
same  vertical  plane  at  the  same  time  that  '  oth  telescopes  are 

143 


!44  THE    SOLAR    TRANSIT. 

carefully  made  horizontal  by  means  of  their  respective  levels. 
Then  measure  the  distance  between  the  axes  of  the  two  tele- 
scopes and  note  whether  the  two  lines  of  sight  of  the  instru- 
ment include  an  equal  space  on  a  rod  set  at  some  distance  from 
the  instrument.  If  they  do  not,  move  the  cross-hairs  of  the  solar 
telescope  until  the  space  included  between  the  lines  of  sight  of 
the  two  telescopes  as  noted  on  the  rod  is  the  same  as  the  dis- 
tance between  the  two  axes  of  the  telescopes  as  previously 
measured. 

METHOD  OF  USING  THE  SOLAR  TRANSIT. 

The  central  principle  to  be  applied  in  the  use  of  the  solar 
transit  is  the  following  :  The  attachment's  axis,  placed  at  right 
angles  to  the  sight  line  of  the  larger  telescope,  can  become  a  true 
polar  axis  only  on  two  conditions  :  First,  that  the  sight-line 
of  the  larger  telescope  lie  in  the  plane  of  the  celestial  equator, 
and  secondly,  that  this  same  sight-line — and  hence  also  the 
"  polar  axis  " — lie  in  the  meri'dian. 

When  the  "  polar  axis  "  is  a  true  one — namely,  lies  in  the  me- 
ridian and  is  also  at  the  elevation  above  the  horizon  equal  to 
the  latitude,  the  solar  telescope  may  be  revolved  upon  the 
polar  axis  in  an  east  and  west,  or  hour-angle  direction  and 
its  line  of  sight  thus,  and  thus  only,  brought  upon  the  sun. 

Conversely,  if  the  proper  setting  be  made,  first  to  the  de- 
clination of  the  sun,  and  secondly  to  the  co-latitude  of  the 
place,  ME,  Fig.  33,  and  the  sun  then  brought  into  the  centre 
of  the  field  of  the  small  solar  telescope  by  simultaneously 
moving^the  main  instrument  on  its  vertical  axis  and  revolving 
the  attachment  on  its  "  polar  axis,"  this  "  polar  axis,"  and 
hence  also  the  l-ine  of  sight  of  the  main  telescope,  must  ha^e 
been  brought  into  the  meridian. 

I.  DETERMINATION  OF  THE  MERIDIAN. 

First,  set  the  solar  telescope  to  the  declination  of  the  sun  by 
the  following  method.  From  the  Nautical  Almanac  find  the 
declination  for  the  day  and  hour  of  the  observation  and  apply 
the  correction  for  refraction  as  explained  later.  Then  incline  the 


THE    SOLAR    TRANSIT.  145 

main  telescope  downwards  from  a  horizontal  position  through 
this  corrected  declination  angle  if  the  sun  is  nortJi  of  the  equator, 
or  incline  it  upwards  if  the  sun  has  a  south  declination. 

Clamp  the  main  telescope  in  this  position  and  then  make 
the  solar  telescope  horizontal  by  means  of  its  attached  level. 
The  solar  telescope  will  thus  have  been  elevated  or  depressed 
through  an  angle  from  its  parallel  position  with  the  main  tele- 
scope equal  to  the  corrected  declination  angle.  Clamp  the 
solar  telescope  on  its  horizontal  axis. 

Secondly,  find  the  co-latitude  of  the  place  of  observation,  if 
it  is  not  known,  by  the  method  given  below,  and  then  elevate 
the  line  of  sight  of  the  main  telescope  through  this  angle  of 
the  co-latitude  by  means  of  the  vertical  circle  of  the  instru- 
ment. 

Thirdly,  by  simultaneously  revolving  the  transit  on  its  ver- 
tical axis,  and  the  solar  attachment  on  its  polar  axis,  bring  the 
sun  accurately  into  the  centre  of  the  field  of  the  solar  tele- 
scope, and  the  line  of  sight  of  the  main  instrument  must  con- 
sequently lie  in  the  plane  of  the  meridian  of  the  place.  The 
direction  of  this  meridian  may  then  be  readily  staked  off  on 
the  ground,  or  the  declination  of  the  magnetic  needle  may  at 
once  be  read  off. 

The  time  of  day  giving  the  best  results  in  the  use  of  the 
solar  transit  is  from  7  to  10  A.  M.  and  from  2  to  5  p.  M.  Earlier 
than  7  A.  M.  and  later  than  5  p.  M.  refraction  introduces  un- 
certain errors.  Between  10  A.  M.  and  2  p.  M.  errors  in  declina- 
tion or  in  latitude  greatly  affect  the  azimuth.  Since  the  hour 
angle  has  different  signs  before  and  after  noon,  the  azimuth 
error  also  changes  sign,  and  the  azimuth  error  due  to  errors  in 
declination  and  in  latitude  are  best  eliminated  by  taking  the 
mean  of  two  observations  made  at  the  same  hour  angle,  one 
before  and  the  other  after  noon. 

II.  DETERMINATION  OF  THE  LATITUDE. 

After  carefully  leveling  bring  the  line  of  sight  of  the  solar 
telescope  into  the  same  plane  with  that  of  the  main  telescope. 
Clamp  the  solar  telescope  upon  its  polar  axis. 

Now  set  off  the  sun's  declination  for  noon  by  the  method 


146  THE    SOLAR    TRANSIT. 

already  described  under  "  Determination  of  Meridian."  Clamp 
the  solar  telescope  upon  its  horizontal  axis. 

Then,  about  ten  minutes  before  the  culmination  of  the  sun, 
begin  observation  for  latitude  by  elevating  the  main  telescope 
and  moving  it  in  azimuth  until  the  sun  is  seen  'in  the  solar. 

By  means  of  the  azimuthal  tangent-screw  and  the  vertical 
tangent-screw  of  the  main  telescope  keep  the  sun  in  the  centre 
of  the  field  of  the  solar  until  the  sun  begins  to  lessen  its  altitude. 

Read  off  the  altitude  of  the  vertical  circle  of  the  instrument 
and  this  will  be  the  co-latitude,  excepting  the  correction  for 
refraction  and  instrumental  errors.  The  correction  for  refrac- 
'tion  for  the  given  altitude  may  be  taken  from  the  "  Table  of 
Mean  Refraction  "  at  the  end  of  this  Manual.  Since  the  effect 
of  these  instrumental  errors  on  the  "  determination  of  the  me- 
ridian "  is  eliminated  by  using  the  value  of  the  co-latitude 
directly  determined  by  means  of  the  instrument,  it  is  usually 
preferable  to  employ  this  value. 

III.  DETERMINATION  OF  THE  TIME. 

The  solar  attachment  sometimes  has  a  small  hour-circle 
attached  to  the  polar  axis,  in  which  case  the  apparent  time 
may  at  once  be  read  off  as  an  hour  angle  of  the  sun  from  the 
meridian.  This  apparent  time  must  then  be  corrected  by  ap- 
plying the  equation  of  time  as  given  in  the  Nautical  Almanac. 

If  no  hour  circle  is  attached  the  time  may  be  found  imme- 
diately upon  getting  the  meridian  by  clamping  both  the  verti- 
cal axis  of  the  main  telescope  and  the  polar  axis  of  the  solar, 
and  then  turning  each  of  the  telescopes  down  on  their  horizon- 
tal axes  until  they  are  level  and  measuring  the  angle  between 
the  two  directions.  This  angle  converted  into  time  will  be 
the  apparent  time,  which  must,  as  before,  be  corrected  for  tfte 
equation  of  time  in  order  to  get  the  mean  time. 

THE  CORRECTIONS  FOR  HOURLY  CHANGE  AND 
REFRACTION. 

The  hourly  change  of  the  declination  is  readily  applied. 
The  solar  ephemeris  of  the"  Nautical  Almanac  gives  the 
declinations  of  the  sun  for  Greenwich  mean  noon  of  the 


THK    SOLAR    TRANSIT.  l^j 

date.  According  as  we  use  "  Eastern,"  "  Central,"  "  Moun- 
tain," or  "  Western"  time,  we  are  approximately  5,  6,  7,  or 
8  hours  west  of  Greenwich,  and  the  declination  of  the 
sun  for  Greenwich  mean  noon  as  given  by  the  ephemeris  is 
therefore  the  declination  at  our  station  for  the  same  date,  but 
either  for  7,  6,  5,  or  4  o'clock  A.  M. 

Knowing  then  the  declination  for  a  given  hour,  we  find  the 
number  of  hours  elapsing  between  that  hour  and  the  time  of 
the  observation,  and  multiplying  the  hourly  change  by  this 
number,  apply  the  result  with  proper  sign  to  the  tabular  dec- 
lination. If  the  standard  time  differs  considerably  from  the 
local  time  the  known  longitude  of  the  place  west  from  Green- 
wich may  be  used  where  extreme  accuracy  is  required. 

The  Refraction  Correction,  whenever  the  altitude  of  the  sun 
is  known,  can  easily  be  taken  from  the  "  Table  of  Mean  Re- 
fraction" placed  among  the  tables  at  the  end  of  this  Manual. 
When  an  observation  is  to  be  made  out  of  the  meridian,  as  is 
usually  the  case  with  the  solar  transit,  the  refraction  correc- 
tion to  the  declination  varies,  not  only  with  the  declination 
but  also  with  "the  hour  angle  of  the  sun  and  with  the  latitude 
of  the  place.  The  correction  may  then  readily  be  computed 
according  to  the  following  formula,  whose  equivalents  are  de- 
rived in  cxtenso  in  works  on  practical  astronomy.  If  we  let  A7 
be  an  auxiliary  angle  such  that 

Tan.  .V  =  Cot.  </>  cos.  /, 

where  $  is  the  latitude  and  /  the  hour  angle,  the  refraction 
correction  to  the  declination,  Cr  is 


where  o  equals  declination,  and  is  plus  or  minus  when  the  sun 
is  respectively  north  or  south  of  the  equator,  and  Ar  is  deter- 
mined by  the  preceding  formula.  Tables  for  a  day's  work  at 
the  given  latitude  of  place  and  for  given  hour  angles  and  dec- 
linations of  the  sun  can  be  readily  prepared  in  advance  by 
means  of  the  latter  formula. 


THE  STADIA 

AND 

THE  GRADIENTER. 


A  DISTANCE-MEASURER  is  an  instrument  furnished 
with  devices  for  determining  distance  from  a  single  point 
of  observation.  The  Germans  call  such  an  instrument 
a  distanzmesser,  and  the  French  designate  it  a  telemeter.  The 
term  tachymeter  has  come  to  be  used  in  Germany  and  else- 
where for  an  instrument  which,  in  addition  to  the  features  of 
an  engineer's  transit,  also  possesses  those  of  a  distance- 
measurer  or  telemeter. 

Two  kinds  of  distance-measurers  are  in  use.  The  first  class 
possesses  in  itself  some  line  which  is  in  fact  the  base  of  the 
triangulation.  The  military  distance-measurers  are  of  this 
class,  and  often  consist  of  two  telescopes  mounted  on  the  same 
base,  and  about  a  meter  apart.  The  second  class  is  charac- 
terized by  measurements  made  upon  a  rod  held  at  the  point 
whose  distance  is  to  be  determined.  This  is  the  only  distance- 
measurer  considered  in  engineering  other  than  military,  and 
we  therefore  limit  ourselves  to  a  review  of  this  class,  or  to  the 
distance-measurer  proper. 

The  simple  basis  of  all  distance  measurements  with  the  rod 
lies  in  the  principle  that  the  same  object  at  a  great  distance 
subtends  a  less  angle  than  when  near  at  hand,  or  that  the  same 
angle  intercepts  more,  say  of  a  rod,  in  proportion  as  the  dre- 
tance  increases. 

The  forms  of  distance-measurers  are  really  quite  numerous, 
if  we  would  include  all  the  European  types.  It  is,  however, 
here  only  necessary  to  speak  of  (i)  The  Vertical  Circle  as  a 
distance-measurer ;  (2)  The  Screw  distance-measurer,  or  Gra- 
dienter.  and  (3)  The  Thread  distance-measurer,  or  Stadia  wires. 

I.  The  Vertical  Circle  of  an  engineer's  transit  or  any  other 
148 


THE   STADIA    AND    THE    GRADIENTER. 


149 


means  for  measuring  vertical  angles,  can  be  used  for  deter- 
mining distance  as  follows : 


Fig.  34. 

Let  PL  represent  a  rod,  to  two  points,  Pl  and  P2  of  which 
the  line  of  sight  is  successively  directed,  and  the  altitudes  a 
and  3,  respectively,  of  the  points  measured.  Let  P1P2  in  Fig.  34 
=  a,  and  P2fi  =  b,  and  hence  P^H  =  a  -j-  b,  and  let  the  dis- 
tance IH  =  D. 

Then  we  have  : 


whence, 


a  -f-  b  =  D  tan.  a,  and  b  =  D  tan.  / 

/7 

(I) 


tan.  a  —  tan.  /? 
or,  for  logarithmic  calculation, 


D=—. 


a  cos.  a  cos.  /? 


(2) 


sin.  (a  —  ft) 

Formulae  (i)  and  (2)  permit  the  distance  to  be  computed  in 
terms  of  an  intercepted  length  on  the  rod,  and  of  two  meas- 
ured angles. 

Incidentally  it  lies  very  near  to  call  attention  to  the  fact  that 
if  heights  instead  of  distances  are  required,  the  following 
formulae  result  as  convenient  for  logarithmic  calculation : 

a  cos.  «sin.  3 


sin.  («  —  ft) 

_  a  sin.  «  cos. 
sin.  («  —  3) 


(3) 


150 


THE    STADIA    AND    THE    GRADIENTER. 


These  formulae  possess,  as  suggested  by  Dr.  Jordan,  some 
decided  advantages  as  a  rapid  means  of  leveling  over  a  rough 
country,  where  the  computations  become  a  secondary  matter. 

THE  GRADIENTER. 

II.  The  Gradienter  is  next  to  be  described  as  a  means  for 
distance-measuring.  It  consists  of  a  finely-cut  screw,  which 
takes  the  place  of  the  vertical  tangent  screw,  and  moves  the 
clamping-arm  attached  to  the  horizontal  axis.  It  acts  against 
a  strong  spring,  so  as  to  produce  positive  motion  of  the  arm 
in  either  direction.  The  screw  has  attached  to  it  a  graduated 
silvered  head  with  fifty  equal  divisions.  Parallel  to  the  screw 
there  is  attached  a  graduated  scale,  which  indicates  the  com- 
plete revolutions  of  the  screw.  The  whole  revolutions  of  the 
screw  are  thus  read  off  on  the  parallel  scale,  and  the  parts  of 
a  turn  on  the  graduated  head. 

The  distance  between  the 
threads  of  this  screw  is  such 
that  a  single  revolution  causes 
the  horizontal  cross-hair  of 
the  telescope  .to  appear  to 
move  over  .01  foot  of  the  rod 
for  one  division,  of  the  gradu- 
ated head  when  the  rod  is  at'a 
distance  of  100  feet  from  the 
instrument. 

This    screw  has  two   chief 

uses,  namely:  (i)  that  of  establishing  grades,  and  (2)  that  of 
measuring  distances.  Grades  may  be  laid  off  by  first  taking 
the  reading  of  the  gradienter  when  the  telescope  is  level,  and 
then  allowing  I  foot  per  loofor  each  division  of  the  graduated 
head,  set  off  to  the  desired  grade.  For  instance,  to  set  off  a 
grade  of  3.45  feet  per  100  feet,  it  is  necessary  to  move  the 
gradienter  3.45  revolutions  of  the  screw. 

A  grade  may  be  measured  by  finding  the  reading  of  the 
gradienter  when  the  telescope  is  level,  and  then  turning  the 
graduated  head  until  the  line  of  sight  points  in  the  proper 


THE    STADIA    AND    THE    GR  ADI  ENTER.  151 

direction,  read  the  number  of  revolutions  and  fraction  of  a 
revolution,  and  this  number  will  be  the  grade  in  feet  per  hun- 
dred. 

Distances  may  be  measured  either  (i)  by  observing  the  dis- 
tance on  the  graduated  rod  passed  over  by  one  revolution  of 
the  screw,  or  (2)  by  taking  an  assumed  length  on  the  rod  and 
finding  the  difference  of  readings  for  this  length.  In  the  latter 
method,  IOO  times  the  assumed  length  on  the  rod  divided  by 
the  difference  of  readings  equals  the  distance  away  of  the  rod, 

GRADIENTER  WITH  LINE  OF  SIGHT  INCLINED. 
It  is  assumed  that  the  rod  is  always  to  be  held  vertically. 
The  use  of  the  rod  at  right  angles  to  the  line  of  sight  is  con- 
sidered to  introduce  additional  trouble  and  error. 


R 


Fig.  36. 

The  theory  of  the  use  of  the  gradienter  for  inclined  sighting 
may  be  readily  inferred  from  Fig.  36 : 

Let  IH '  =  D  =  Horizontal  distance  of  the  point. 
IP  =  Dx  =  Direct  distance  of  the  point. 
PO  =  r  =  Length  of  the  vertical  rod  included  by  the 
angle  /. 

PR  =  rt  =  Length  of  inclined  rod  included  by  the 
angle  /. 

Then  D  tan.  («  +  >)  =  /?  tan.  a  +  r.  (i) 


or  D=- 


tan.  (a 


—  tan.  « 


(2) 


152  THE    STADIA    AND    THE    GRADIENTER. 

whence,  by  development  and  transformation, 

D  =  r  (cot.  7  cos.2  a  —  sin.  a  cos.  a)  (3) 

and,  finally,  D  =  r  (cot.  y  cos.2  a  —  ^  sin.2«)  (4) 

Dividing  (3)  by  cos.  a  we  get 
i  Dl  =  r  (cot.  7  cos.  «  —  sin.  a)  (5) 

If,  in  the  second  terms  of  equations  (4)  and  (5)  we  add  and 
subtract  r  cot.  7,  we  get  the  following  forms,  which,  involving 
only  the  sine,  are  adapted  to  accurate  computation  : 

I)  =  r  cot.  7  —  r  (cot.  y  sin.2  a  +  ^  sin.2  «)  (6) 

Z?j  =  r  cot.  7  —  r  (cot.  7  2  sin.2  ^  a  +  sin.  a)  (7) 

The  latter  formulae  (6)  and  (7),  although  frequently  used,  do 
not  give  the  tabular  factors  in  quite  as  convenient  a  form  as 
formulae  (4)  and  (5). 

If  we  let  cot.7  —  100,  the  value  usually  adopted  in  QUEEN 
&  Co.'s  gradienters,  and  also  let  100  cos.2  a.  —  y^  sin.  2  a  =  F 
and  100  cos.  a  —  sin.  a  =  Flt  the  formulae  (4)  and  (5)  assume 

the  form 

D  =  rF' 


that  is,  simple  multiplication  of  the  difference  of  two  readings 
on  the  rod,  r,  by  the  proper  factor,  gives  either  the  horizontal 
distance,  or  the  direct  distance,  as  desired.  The  values  of  F 
and  Fl  are  given  in  Tlie  Gradicnter  Table  at  the  end  of  this 
Manual. 

THE  STADIA  METHOD. 

III.  The  Stadia  wires,  so-called,  are  inserted  in  the  common 
focus  of  the  objective  and  eye-piece.  The  accompanying 
figure  will  show  the  arrangement  of  the  wires,  the  three  hori- 
zontal being  used  for  stadia  purposes.  The  distance  between 
the  central  and  lower  or  upper  one  may  sometimes  be  con- 


THE   STADIA    AND   THE    GR  ADI  ENTER. 


153 


veniently  used  instead  of  the  distance  between  the  upper  and 

lower. 

In  many  instances  the  wires 
are  made  adjustable  so  that  they 
may  be  set  for  a  distance  of  a 
hundred  feet  from  the  front  focus 
of  the  objective.  In  QUEEN  & 
Co.'s  instruments  the  upper  and 
lower  wires  are  simultaneously 
adjustable  from  the  central  wire 
by  means  of  the  movable  pieces 
Fi  marked  a  a  in  the  figure. 


THE  OPTICAL  THEORY  OF  THE   STADIA. 

If  a  Ramsden's  ocular  or  its  equivalent  is  used,  the  rela- 
tions between  the  factors  may  be  diagrammatically  represented 
by  the  accompanying  figure  in  which  0  represents  the  objec- 
tive of  the  telescope,  E  the  eye-piece,  iv  the  interval  between 
the  wires,  r  the  length  intercepted  on  the  rod  by  the  wires,/ 


-D 


* d -t 


Fig.  38- 

the  focal  length  of  the  object  glass,  D0  the  distance  of  the  rod 
from  the  objective,  Df  the  distance  of  the  rod  from  a  point  in 
front  of  the  object  glass  equal  to  the  focal  length  /,  d  the 
distance  of  the  wires  from  the  objective.  Then  from  the  prin- 
ciples of  optics  we  have  : 


- 

f 


— 

D, 


and  from  the  figure  we  have  by  similar  triangles; 


154  THE    STADIA    AND    THE  .GRADIENTER. 

w         r  ,  s 

7  =  A  <2> 

From  the  equations  (i)  and  (2)  we  readily  derive  the  follow- 
ing: 

*•-/  =  •£  r  (3) 

or     Df=r-f-    r 

w 

Accordingly  D/y  or  the  distance  of  the  rod  from  the  front 
focus  is  p/oportional  to  the  length,  r,  intercepted  on  the  rod. 
It  is  to  be  particularly  noted  that  this  distance  Df  and  no 
other  is  the  one  to  which  the  intercepted  rod  readings,  1-,  are 
proportional. 

It  is  not  worth  while  here  to  indicate  the  special  modifica- 
tions of  this  simple  theory,  necessary  to  adapt  it  to  the  cases 
of  the  Huyghenian  eye-piece,  or  that  of  the  Porro  eye-piece, 
the'  'latter  having  been  specially  designed  to  make  the  intercept 
on  the  rod  proportional  to  the  distance  of  the  rod  as  measured 
from  the  centre  of  the  instrument. 

If  now  we  let  Dc  equal  the  distance  of  the  stadia  rod  from 
the  centre  of  the  instrument  and  d  equal  the  distance  of  the 
objective  from  the  centre  of  the  instrument  when  the  telescope 
is  focused  for  the  average  of  distances,  we  have : 

Dc  ==  D0  +  3, 
and  inserting  the  value  of  D0  from  equation  (3),  we  have  : 

Dc=f+B+{-r  (4) 

where/-f  o  is  a  constant  peculiar  to  the  particular  instrument. 
Therefore,  letting  c  —f-\-  d, 

Dc  =  c+l-r  (5) 

W 

Further — -is    the  coefficient    of  the    instrument  depending 


THE    STADIA    AND    THE    GRAD1ENTER. 


155 


upon  the  focal  length  of  the  objective  and  the  distance  apart 
of  the  wires,  and  therefore  letting  K  =  —  equation  (5)  now 


becomes, 


whence 


DC  =  c  4-  Kr 


D  —  c= 


(6) 

(7) 


PRACTICAL    DETERMINATION    OF   THE    STADIA 
CO-EFFICIENT. 

As  a  practical  illustration  of  the  formulae  last  found,  the 
following  example  is  added  : 

Determine  c  =/+  d  by  actual  measurement  of /and  of  d. 
Let,  for  example,  c=  1.5 'feet.  Then  measure  .1.5  feet  from 
the  plumb-line,  depending  from  centre  of  instrument,  and  mark 
it  by  a  stake.  This  stake  will  be  f  in  front  of  the  objective. 
Call  this  point  so  marked  A.  From  A  measure  and  stake  off 
the  50  foot  point,  the  100  foot  point,  150  foot  point,  200,  250, 
etc.,  to  500  or  1,000.  Dc  being  the  whole  distance  from  centre 
of  instrument,  and  c  the  distance  of  stake  A,  each  of  the 
measured  distances  50  feet,  100  feet,  etc.,  beyond  A  represents 
Dc  —  c  in  formula  (5),  while  r  represents  the  particular  rod 
reading  for  each  case.  The  following  represents  a  number  of 
rod  readings  at  Dc  —  c  distances.  Five  independent  readings 
are  taken  for  each  point : 


Dc  —  c 
Feet.         (i) 
50        0.501 
IOO 
150 


I.OOO 

1.501 


Rod  Readings. 

(2)               (3)"                (4) 

(5) 

0.501         0.501         0502 

0.500 

I.OOO         I.OOO         1.  001 

1.002 

1.503     1.501      1.500 

1.502 

Dc—c 
Mean  R.    — - — 

Feet. 

0.5010  99.804 

1.0006  99.940 

1.5014  99.907 


200         2.005         2.007         2.002         2.005          2.005         2.0048         99761 


4)399-412 


Practically,  99.85  =  K. 


99.853  = 


In  the  QUEEN  &  Co.  instruments   K  is   usually  made  equal 
to  100.     Since  this   factor  K,  multiplied  into  r,  gives  the  D} 


156 


THE    STADIA    AND    THE    GRADI ENTER. 


distance  and  not  the  De  distance  desired,  the  following  method 
of  adjusting  the  wires  may  sometimes  be  advantageously 
adopted.  The  formula  (6)  may  be  written  in  the  form  : 


Now  if h  K  be  made  equal  to   100,  the  readings  of  the 

rod  mentally  multiplied  by  IOD,  would  give  the  distance  from 
the  centre  of  the  instrument.  Accordingly  we  must  take, 

K=  100 — —  For  example  let  r=  1.5  feet  corresponding 
to  1 50  feet  as  the  average  of  distances  it  is  desired  to  measure. 
Then  K=  100  —  —  =  99,  and  Dc  —  loor,  as  desired. 

STADIA  WITH  INCLINED  LINE  OF  SIGHT. 
The  use  of  the  stadia,  as  thus  far  explained,  is  adapted  only 
to  horizontal  sighting.  If  the  line  of  sight  is  inclined  to  the 
horizon,  the  rod-reading  becomes  greater,  and  varies  with  the 
inclination.  The  general  formulae  for  any  case  may  be  derived 
from  the  accompanying  figure,  in  which  a  represents  the  angle 
of  elevation  or  depression,  r  the  intercepted  portion  of  the  rod 
when  held  vertical ;  and  hence,  r  cos.  a  the  intercepted  portion 


Fig.  39- 

of  the  rod  when  held  at  right  angles  to  the  direction  of  the 
line  of  sight.     IP  or  direct  Dc>  equals  the  direct  distance,  arid 


THE    STADIA    AND    THE    GRADIENTS!*.  157 

IQ,  or  horizontal    DCt  equals    the  horizontal  distance.     But, 
evidently,  for  direct  distance  from  the  front  focus  we  have: 

D/=  Kr  cos.  a 
Whence, 

Direct  Distance  =  IP  =  c  +  Kr  cos.  a  (8) 

Horizontal  Distance  =  IQ  =  c  cos.  «  +  Kr  cos.2#        (9) 
and 

Difference  of  Level  =  PQ  =  c  sin.  «  -f-  /4  Kr  sin.  2«      (10) 

These  formulae  very  closely  approximate  to  the  strictly 
mathematical  conditions.  A  very  small  error  is  committed  in 
assuming  that  r  cos.  a  represents  the  intercepted  portion  of  the 
rod  when  the  rod  is  held  at  right  angles  to  the  line  of  sight, 
since  the  rod  is  not  within  a  few  minutes  of  arc  of  90°  to  PR 
and  PS.  Again,  for  77)  the  horizontal  distance  to  the  foot  of 
the  rod,  7*5"  sin.  a  would  have  to  be  added  or  subtracted,  ac- 
cording to  the  inclination  of  the  rod.  But  this  also  is  small 
enough  to  be  omitted  in  ordinary  work.  The  formulae  (9)  and 
(10)  are  the  practical  general  formulae  for  the  stadia,  giving 
respectively  the  horizontal  distance  and  the  difference  of  level. 

The  most  complete  tables  adapted  to  these  formulae  are  the 
"  Hulfstafeln  fur  Tachymetrie"  by  Dr.  W.  Jordan.  The  use 
of  these  tables  obviates  all  inconvenient  arithmetical  operations 
or  the  study  of  complicated  reduction  diagrams ;  and  the 
heights  and  distances  can,  for  ordinary  accuracy,  be  directly 
taken  from  the  tables,  without  interpolation.  QUEEN  &  Co. 
furnish  a  special  translation  of  the  introduction  to  this  work, 
and  an  adaptation  of  the  tables  to  convenient  use  with  any  of 
their  instruments. 


158 


TABLES. 


OR  ADI  ENTER    TABLE. 


o 

w            o° 

c 

e                          y 

I 

*     i 

s 

1    ll 

.5     «£  s 

•i    «2a 

•I     &  g 

J) 

f  u^- 

tT~  2 

1 

^     fa~Q 

1        Ctf  •" 

o 

SO** 

o  *j 

S  e 

J3   °  £  | 

S  °fi 

*5b 

8    £•§ 

O           U    u 
8ti<  VT 

u 

M 

ui       £  o 

o     o  iJ 

1 

8       £ 

Q 

c 

o      fc  o 

°      ffi 

o      ^Q 

o           / 

\ 

o          / 

OO      OO 

IOO.OO                     IOO.OO 

15     oo             93.05 

96.33 

o     30 

99.98- 

99.99 

15       30                  92.60 

96.09 

I       00 

99-95 

99-97 

16     oo    :          92  14 

9585 

I    30 

99-90 

99-94 

16     30             91.66 

0560 

2      00 

99-84 

99.90 

17     oo             91.17 

95-34 

2       30 

99-76 

99.86 

17     30 

90.67 

95-°7 

3      0° 

99.67 

99.81 

18    oo 

90.16 

94.80 

3     30 

99-57 

99-75 

18     30 

89.63 

94-51 

4    oo 

99-44 

9969 

19    oo 

89.09 

9423 

4    30 

99.21 

99.61 

19   30 

88.54 

93-93 

5     oo 

99-15 

99.53 

20      00 

87.98 

93-63 

5     30 

98.98 

99-44 

2O      30 

87.42 

9332 

6    oo 

98.80 

99-35 

21       00 

86.82 

93-0° 

6     30 

98.60 

99.24 

21       30 

86.22 

92.67 

7     oo 

98.39 

99.13 

22      00 

85.62 

92-34 

7     30 

98.16 

99.01 

22       30 

85.00 

92.00 

8    oo 

97.93 

98.89 

23     oo 

84.37 

91.66 

8    30 

97.67 

98.75 

23       30 

83-73 

91.31 

9    oo 

97.40 

98.61 

24     oo 

8308 

90.95 

9     30 

97.11 

98.46 

24   30 

82.43 

90.58 

IO      OO 

96.81 

98-31 

25     oo 

81.76 

90.21 

10     30 

96.50 

98.14 

25     3° 

8  1.  08 

89-83 

II       00 

96.17 

97-97 

26     oo 

80.39 

89.44 

II     30 

95.83 

97-79 

26     30 

79-69 

89-05 

12      OO 

95-47 

97.61 

27     oo 

78.98 

88.65 

12       30 

95-10 

97-41 

27   30 

78.27 

88.24 

13     oo 

94.72 

97-21 

28     oo 

77-54 

87.82 

13       30 

94-32 

97.00 

28    30 

76.81 

87.40 

14    oo 

93-93 

96.79 

29    oo 

7607 

86.98 

14     3° 

9349 

96-56 

29   30 

•    75-32 

86.54    • 

15     oo 

93-05 

96.33 

30    oo 

74.56 

86.10    » 

NOTE. — The  difference  of  the  rod-readings  r,  for  loo  divisions  of  the  graduated 
head  of  the  Gradienter  screw,  multiplied  by  f\  gives  the  horizontal  distance  of 
the  rod  from  the  horizontal  axis  of  the  telescope ;  the  same  r,  multiplied  by  F^ 
gives  the  direct  distance. 


TABLES. 


159 


TABLE  OF  MEAN  REFRACTION. 

Temperature,  50°  F.     Barometric  Pressure  Reduced  to  50°  /".,  jo  in. 


Apparent 
Altitude. 

I 

Mean                   Appirent      \ 
Refraction.             Altitude. 

I1 

Mean 
Refraction. 

Apparent 
Altitude. 

Mean 
Refraction. 

o°oo" 

33/47-9//          i6°oo/ 

3'  20.8" 

41°  oo'            i7  07.0" 

I     OO 

24   22.3 

17   oo 

3  08.6 

42   oo             i   04.7 

2    00 

18   23.1 

18  oo 

2     57-7 

43   oo       j       i   02.5 

3   oo              14  28.7 

19  oo 

2  47-8 

44   oo             i   00.3 

4  oo 

II     48.8^                20    00 

2    38.9 

45   oo 

o   58-3 

5   oo 

9   54.8             21   oo 

2    30.8 

46  oo 

o   56.3 

6  oo 

8   30-3 

22    OO 

2     23.4 

48  oo             o   52.5 

6   30 

7   55-9 

23  oo 

2     16.6 

50  oo 

o  48.9 

7   oo 

7    25.6 

24  oo 

2     IO.3 

52   oo 

o  45-5 

7   30 

6   58.7 

25   oo 

2    04.5 

54  oo 

o  42.3 

8  oo 

6  34-7 

26  oo 

I     59-0 

56  oo 

o  39-3 

8   30               6    13.2            27   oo 

I     54.0 

58  oo 

o  36-4 

9  oo                5   53.7            28  oo 

I    49-3 

60  oo 

o  33  7 

93°                5   36.0            29  oo 

I   44-8 

62   oo 

o   31.0 

10    00 

5    20.0 

30  oo 

i    40.7 

64  oo 

o  28.4 

10  30 

5   05.4 

31   oo 

I    36.8 

66  oo 

o   26.0 

II     00 

4   5i-9 

32   oo 

i   33-1 

69  oo 

o   22.4 

ii    30 

4  39-5 

33  0° 

i    29.6 

72   oo 

o   19.0 

12    OO 

4   28.1 

34  oo 

i    26.2 

75   oo 

o    15.6 

12     30 

4   17-5 

35   oo 

i    23.1 

78  oo 

o   12.4 

13   oo 

4  07.7 

36  oo 

I     20.1 

80  oo 

o   103 

13  30 

3   58.5 

37   oo 

I     17.2 

83   oo 

o  07.2 

14  oo 

3   So.o 

38  oo 

I     H5 

86  oo 

O    04.  T 

14  3° 

3   42.o 

39  oo 

i    ii  9 

89  oo 

O    OI  O 

15   oo 

3   34-4 

40  oo 

i   09.4            90'  oo 

o  oo.o 

THE    SEXTANT. 


THE  Cut  shows  the  details  of  construction  of  the  Sextant. 
ABC  is  a  light  frame  work  of  brass  in  the  shape  of  a 
sector  of  60  degrees,  the  limb  AB  having  a  graduated  arc 
of  silver  (in  some  cases  of 
gold)  inlaid  in  the  brass.  It 
is  held  in  the  hand  by  a  small 
handle  at  the  back,  either  ver- 
tically to  measure  the  altitude 
of  an  object,  or  in  the  plane 
passing  through  two  objects, 
the  angular  distance  of  which 
is  to  be  found.  CD  is  a  radius 
movable  around  C,  where  a 
small  plain  mirror  of  silvered 
plate  glass. is  fixed  perpendic- 
ular to  the  plane  of  the  sex- 
tant and  in  the  line  CD.  At 
D  is  a  vernier  read  through  a 
small  lense,  also  a  clamp  and 
a  tangent  screw  which  enable  the  observer  to  give  the  arm  CD 
a  very  slow  motion  within  certain  limits.  At  E  is  another 
mirror  "  the  horizon  glass."  Also,  perpendicular  to  the  plane 
of  the  sextant  and  parallel  to  CD,  F  is  a  small  telescope  fixed 
across  CB,  parallel  to  the  plane  CAB,  and  pointed  to  the  mir- 
ror E.  Dark  glasses  can  be  placed  outside  E  and  between  E 
and  C  when  observing  the  sun. 

As  only  the  lower  half  of  E  is  silvered,  the  observer  can  ^ee 
the  horizon  in  the  telescope  through  the  unsilvered  half,  while 
the  light  from  the  sun  on  a  start  6*  may  be  reflected  from  the 
' '  index  glass  "  C  to  the  silvered  half  of  E  and  thence  through 
.Fto  the  observer's  eye,  If  CD  has  been  moved  so  as  to  make 
the  image  of  a  star  or  of  the  limb  of  the  sun  coincide  with  that 
of  the  horizon,  it  is  easy  to  see  that  the  angle  SCH  (the  alti- 
tude of  the  star  or  solar  limb)  is  equal  to  twice  the  angle  BCD. 
1 60 


THE   SEXTANT.  l6i 

The  limb  AB  is  graduated  so  as  to  avoid  the  necessity  of 
doubling  the  measured  angle,  a  space  marked  as  a  degree  on 
the  limb,  being  in  reality  only  30'.  The  vernier  should  point 
to  o°  c'  c  '  when  the  two  mirrors  are  parallel,  or,  in  other  words, 
when  the  direct  and  reflected  images  of  a  very  distant  object 
are  seen  to  coincide. 

When  the  sextant  is  used  on  land  an  artificial  horizon  is  re- 
quired. This  is  obtained  by  employing  a  basin  of  mercury 
protected  by  a  roof  of  plate  glass  with  perfectly  parallel  faces, 
which  is  levelled  on  three  screws  by  spirit  levels. 

The  telescope  being  directed  to  the  image,  the  celestial  object 
reflected  from  the  artificial  horizon  and  this  image  is  made  to 
coincide  with  that  reflected  from  the  object  glass.  In  this  case 
the  angle  BCD  will  be  double  the  altitude  of  the  star. 


THE    ANEROID    BAROMETER. 


THE  word  Aneroid,  from  the  Greek  privative  ay  and  neros 
wet,  suggests  the  character  of  this  instrument,   whose 
indications  are  obtained  by  the  pressure  of  the  atmos- 
phere upon  a  delicate  metal  box,  exhausted  of  air,  instead  of, 
as  in  the  Mecurial  Barom- 
eter,   by   the   height    of    a 
fluid  column. 

Invented  about  the  be- 
ginning of  the  present  cen- 
tury, it  was  not  until  about 
1848  that  the  difficulties  in- 
volved in  the  construction 
of  such  an  instrument  were 
overcome,  and  the  present 
serviceable  form  devised  by 
M.  Vidie. 

Since  that  time,  the  Aneroid  has  continued  substantially  the 
same  ;  improvements  being  rather  in  the  direction  of  more 
perfect  workmanship  in  its  parts,  and  in  the  more  perfect 
adaptation  of  its  metals,  than  in  any  change  of  form. 

As  shown  in  the  illustration,  the  Aneroid  consists  of  a  flat 
cylindrical  vacuum  box,  the  upper  surface  of  which  is  cor- 
rugated, in  order  that  it  may  yield  more  readily  to  external 
pressure.  The  lower  surface  of  the  vacuum  chamber  is  firmly 
fixed  at  the  center  to  a  strong  foundation  plate,  -whilst  at  the 
center  of  the  upper  surface  is  a  metallic  pillar  C,  which  acts 
upon  a  powerful  steel  spring  D. 

The  varying  atmospheric  pressure  causes  the  surface  of  the 
vacuum  chamber  to  rise  and  fall ;  these  movements  are  trans- 
mitted to  the  spring,  and  thence  by  two  levers,  G  and  H,  to  a 
metallic  axis  /.  From  the  latter  rises  a  lever/,  to  whose  ex- 
tremity a  chain  Q  is  attached,  which  turns  a  drum,  the  axis  of 
which  bears  the  index  needle.  A  firm  spiral  spring  keeps  the 
chain  constantly  in  proper  tension.  By  this  arrangement  of 
162 


TIIK    ANERIOD    BAROMETER.  163 

multiplying  levers,  a  very  small  movement  of  the  surface  of 
the  vacuum  chamber  causes  a  large  deviation  of  the  needle  ; 
of  an  inch  causing  it  to  move  through  a  space  of  3  inches. 


Fig.  A. 

Figure  A  shows  a  section  of  the  vacuum  box  ;  B  being  the 
pillar  to  which  the  main-spring  is  attached  ;  L  the  attachment 
to  foundation  plate  ;  D  the  tube  through  which  the  box  is  ex- 
hausted, and  a,  a,  a,  a,  the  overlapping  thin  German  silver 
corrugated  plates. 


Fig.  B. 

In  figure  B,  we  have  the  chamber  exhausted  of  air ;  the 
dotted  lines  showing  the  tension  to  which  the  instrument  is 
brought,  and  enabling  it  to  be  understood  how  readily  the  in- 
strument may  respond  to  the  varying  atmospheric  pressure. 
Compensation  for  temperature  is  effected,  as  in  chronometers, 
by  an  adjustment  of  brass  and  steel  in  the  main  lever,  by  whose 
unequal  expansion  and  contraction  the  liability  to  error  from 
change  of  temperature  is  overcome. 

The  dial  is  graduated  arbitrarily  to  correspond  with  the  mer- 
curial barometer,  after  the  instrument  is  tested  under  the  air- 
pump  to  find  the  range.  It  is  apparent,  therefore,  that  the 
Aneroid  can  never  be  used  as  an  independent  standard,  but 
must  be  frequently  compared  with  the  mecurial  barometer. 


1 64  THE   ANEROID   BAROMETER. 

When  so  compared,  however,  and  adjusted  by  a  Mercurial 
Standard,  the  Aneroid  possesses  several  advantages  over  the 
former.  It  is  extremely  portable  and  can  be  carried  in  any 
way,  or  subjected  to  any  motion  without  danger  of  disturbance 
of  its  indications.  It  is  not  at  all  liable  to  get  out  of  order — 
is  not  easily  broken,  and  lastly,  it  is  very  much  more  sensitive 
than  the  Mecurial  Barometer. 

The  late  Admiral  Fitzroy,  Mr.  Glaisher  the  aeronaut,  and 
many  other  authorities,  testify  to  the  extreme  sensibility  of  the 
Aneroid  ;  the  former  particularly  noting  ' '  its  quickness  in 
showing  the  variations  of  atmospheric  pressure."  Kven  in 
observatories,  therefore,  where  Mercurial  Standards  are  in  use, 
the  Aneroid  is  most  valuable  in  its  capacity  of  giving  earlier 
indications  than  can  be  obtained  from  the  more  sluggish  mer- 
curial column. 

To  the  seaman,  who  has  often  extreme  difficulty  in  using 
the  barometer  from  the  pumping  of  the  mercury  caused  by  the 
vessel's  motion,  the  Aneroid  is  indispensable ;  and  from  its 
greater  delicacy,  he  can  often  prepare  for  a  change  in  weather 
a  considerable  time  before  the  Mercurial  Barometer  gives  evi- 
dence of  an  impending  storm. 

The  value  of  the  Aneroid  in  ascertaining  differences  of  alti- 
tude, is  obvious,  and  of  this  we  speak  more  fully  in  the  suc- 
ceeding pages. 

THE  USE  OF  THE  ANEROID   FOR  ALTITUDE. 

From  its  portability,  sensitiveness,  and  the  ease  with  which 
approximate  altitudes  may  be  ascertained,  the  Aneroid  Barom- 
eter is  very  valuable  to  the  engineer.  In  preliminary  surveys 
and  reconnoissances  it  has  been  found  extremely  useful,  and 
for  these  purposes  it  is  largely  employed.  Carrying  one  of 
these  little  instruments,  the  size  of  which  need  not  exceed  two 
or  three  inches  in  diameter,  the  engineer,  riding  rapidly  over  a 
country,  can  speedily  and  with  ease  procure  the  data  for  the 
determination  of  the  line  of  a  survey.  Holding  an  Aneroid  in 
his  hand,  the  traveller  seated  in  the  railroad  car,  can  mark  the 
changes  of  elevation  as  his  train  moves  ;  the  mountain  climber 
can  note,  step  by  step,  his  gain  in  altitude  ;  and  the  miner, 
with  the  new  mining  Aneroid,  can  measure  his  descent  in 
single  feet. 


THE   ANEROID    BAROMETER.  165 

We  have  elsewhere  explained  the  principle  of  the  Aneroid, 
and  the  manner  in  which  its  indications  are  obtained,  and  have 
referred  to  the  necessity  of  accurate  workmanship  in  its  con- 
struction, and  of  intelligence  and  skill  in  its  examination  and 
adjustment.  For  hypsometrical  work,  it  is  especially  im- 
portant that  the  Aneroid  should  be  absolutely  accurate  ;  that 
its  compensation  for  effect  of  temperature  on  the  metallic  works 
be  perfect,  and  that  its  indications  should  be  identical  with 
those  of  the  mercurial  column.  The  importance  of  compensa- 
tion, particularly  for  Pocket  Aneroids,  is  evident  when  it  is 
remembered  that  the  change  from  a  room  to  the  external  atmos- 
phere may  frequently  involve  a  difference  in  temperature  of 
from  30°  to  50°  F.,  a  difference,  which,  without  proper  com- 
pensation, may  move  the  needle  through  a  space  equal  to  one 
hundred  or  more  feet.  It  is  also  necessary  that  the  Aneroid 
be  tested  for  correspondence  with  the  mercurial  column.  If 
the  scale  of  the  Aneroid  be  accurately  divided  and  in  accord 
with  the  instrument  itself,  the  needle  will  move  tenth  by  tenth, 
with  the  mercurial  column,  in  perfect  coincidence. 

There  are  many  good-working  Aneroids  in  use,  which  do 
not  thus  correspond  with  the  Mercurial  Barometer,  and  whose 
constants  of  error  being  unknown,  give  inaccurate  results. 
Such  barometers  could  be  used  with  satisfaction  if  their  correc- 
tions were  known  ;  and  all  Aneroids  require  to  be  periodically 
tested — adjusted  to  accord  with  the  Standard  Mercurial  Barom- 
eter, and  their  corrections,  if  any  are  necessary,  ascertained. 

CORRECTIONS   DEPENDENT   UPON   PHYSICAL 

LAWS. 

In  strictly  accurate  observations,  it  is  necessary  that  the 
Aneroid,  as  well  as  the  Mercurial  Barometer,  should  be  used 
with  formulas  for  various  corrections.  The  corrections,  how- 
ever, for  gravity,  for  temperature  of  the  mercury,  and  for 
capillary  attraction  are  of  course  unnecessary  with  the  Aneroid; 
and.  indeed,  for  all  ordinary  work,  the  only  correction  required 
is  that  for  the  temperature  of  the  atmosphere,  \vhich  need  only 
be  considered  when  the  temperature  is  above  or  below  50°  F. 

It  must  of  course  be  remembered,  in  using  a  barometer  of 
any  kind  for  the  purpose  of  ascertaining  the  altitude  of  a  place, 
that  while  the  normal  barometric  pressure  is  assumed  to  be 


1 66  THE    ANEROID    BAROMETER. 

represented  by  a  mercurial  column  of  about  30  inches  at  sea- 
level,  it  is  but  occasionally  that  this  is  actually  attained.  The 
variations  of  atmospheric  pressure  are  continual,  the  periodic 
fluctuations  being  considerable,  and  the  nonperiodic  oscilla- 
tions so  great  and  so  irregular,  that  it  is  only  by  taking  the 
mean  of  a  long  series  of  observations  that  the  periodical  varia- 
tions can  be  ascertained.  It  follows,  therefore,  that  a  single 
reading  of  the  barometer  can  never,  save  by  the  rarest  chance, 
indicate  an  absolute  elevation. 

Aneroids  for  altitudes  may  be  used  with  the  ordinary  scale 
of  inches  and  tenths,  or,  as  they  are  now  more  usually  arranged, 
.with  a  graduated  circle  of  feet  in  addition. 


TO   MEASURE   ALTITUDES   WITH   ANEROID 

BAROMETER, 
Without  Altitude  Scale. 

Roughly  speaking,  the  barometer  falls  one  inch  for  every 
900  feet  of  ascent ;  or  at  mean  atmospheric  pressure  in  this 
latitude. 

Above  sea -level 

917  feet,  the  barometer  falls        .          .          .          .          i  inch. 
1860    "       "  "          ....         2  inches. 

2830    "  "  3       " 

3830    "       "  "  4       " 

4861     "  "  5       " 

TO    FIND   THE   RELATIVE   HEIGHT   OF  TWO 
GIVEN   PLACES. 

Take  a  reading  of  the  Aneroid  at  first  station  ;  subtract  from 
this  the  reading  at  the  second  station.  The  product  multiplied 
by  9  will  give  the  difference  of  altitude  in  feet,  thus  ; 

First  Station,        .         .         .         .         .         30  20 
Second  Station,   .          .         .         .         .         29  99 


21 
9 


Difference  of  altitude,  .          .         .  189  feet. 


THE   ANEROID    BAROMETER. 


This  under  ordinary  pressures  and  with  a  temperature  about 
50°  K.  will  give  good  results.  If  the  temperature  is  over  70^ 
F.,  multiply  by  10. 

The  table  prepared  by  Mr.  Symons  is  more  strictly  accurate: 


Mean  Temperature. 

30° 

40° 

50° 

60° 

?o° 

80° 

Mean  pressure,  27  inches. 
28       " 
11            "          29       " 
30 

9-7 
9-3 
9.0 

8.7 

9.9 

9-5 
9.2 

8.9 

10.  1 

9.8 

9-4 
9.1 

10.3 

10.  0 

9.6 
9-3 

10.5 

10.2 
9.8 

9-5 

10.8 
10.4 

10. 

9-7 

The  best  results  may,  however,  be  obtained  by  the  use  of 
the  table  prepared  by  Sir  G.  Airy,  late  Astronomer- Royal  of 
England. 

TO  USE  AIRY'S  TABLE, 
With  mean  temperature  at  50°. 

Take  the  reading  in  inches  of  the  barometer  scale,  at  the 
lower  and  upper  stations.  Find  in  the  table  the  heights  in  feet, 
corresponding  to  the  barometer  readings.  Subtract  them  and 
the  remainder  will  be  the  height  required. 

When  the  mean  temperature  is  above  or  below  50°  F.,  the 
following  correction  must  be  applied  :  add  together  the  temp- 
erature of  the  upper  and  lower  stations .  If  the  sum  is  greater 
than  100°  F.,  increase  the  height  by  yoW^  Part  for  ever7 
degree  of  the  excess  above  100°  ;  if  the  sum  is  less  than  100°, 
diminish  the  height  by  1  ^  6  th  part  for  every  degree  less  than. 
1 00°.  The  complete  formula  is  : 


T  and  t  are  the  observed  temperatures ;  H  and  h  are  the  heights 
in  feet  taken  from  the  table. 


1 68 


TABLES. 


AIRY'S   TABLE. 

Arranged  for  temperature  of  50°  F. 


Height  Aner°id 
or 

Height 

Aneroid 
or 

Height 

Aneroid 
or 

Height 

Aneroid 
or 

i  Corrected 

in 

Corrected 

in 

Corrected 

in 

Corrected 

feet 

feet. 

feet. 

feet. 

Barometer 

Barometer. 

Barometer. 

Barometer. 

ft.       in. 

ft. 

in. 

ft. 

in. 

ft. 

in. 

o  31-000 

1850 

28-966 

3700 

27-065 

15550 

25-289 

50   30-943 

1900 

28-913 

3750 

27-015 

5600 

25-242 

100 

30-886 

1950 

28-860 

3800 

26-966 

5650 

25-196 

150 

30-830 

2000 

28-807 

3850 

26-916 

5700 

25-I50 

200 

30-773 

2050 

28-754 

3900 

26-867 

5750 

25-I04 

250 

30-717 

2IOO 

28-701 

3950 

26-8I8 

5800 

25-058 

300 

30-66I 

2150 

28-649 

4000 

26-769 

5850 

25.012 

350 

30-604 

22OO 

28-596 

4050 

26-720 

5900 

24-966 

400 

30-548 

2250 

28-544 

4100 

26-671 

5950 

24-920 

450 

30-492 

2300 

28-491 

4150 

26-622 

6OOO 

24-875 

500 

30-436 

2350 

28-439 

42OO 

26-573 

6050 

24-829 

550 

30-38I 

2400 

28-387 

I4250 

26-524 

6lOO 

24-784 

6OO 

30-325 

2450 

28-335 

J4300 

26-476 

6150 

24-738 

650 

30-269 

2500 

28-283 

I  4350 

26-427 

6200 

24-693 

7OO 

30-2I4 

2550 

28-231 

4400 

26-379 

6250 

24-648 

750 

30-I59 

26OO 

28-180 

4450 

26-330 

6300 

24-602 

800 

30-I03 

2650 

28-128 

45oo 

26-282 

6350 

24-557 

85-0 

30-048 

27OO 

28-076 

4550 

26-234 

6400 

24-512 

9OO 

29-993 

2750 

28-025 

4600 

26-I86 

6450 

24-467 

950 

29-938 

2800 

27-973 

14650 

26-138 

6500 

24-423 

IOOO 

29-883 

2850 

27-922 

47oo 

26-090 

6550 

24-378 

1050 

29-828 

29OO 

27-871 

4750 

26-042 

6600 

24-333 

1  100 

29-774 

2950 

27-820 

4800 

25-994 

6650 

24-288 

1150 

29.719 

3000 

27-769 

4850 

25-947 

6700 

24-244 

I2OO 

29-665 

3050 

27-718 

4900 

25-899 

6750 

24-2OO 

1250 

29-610 

3100 

27-667 

4950 

25-852 

6800 

24-I55 

1300   29-556 

3150 

27-616 

5°oo 

25-804 

6850 

24-III 

I35C 

29-502 

3200 

27-566 

5050 

25-757 

6900 

24-067 

1400 

29-448 

3250 

27-5I5 

5100 

25-710 

6950 

24-023 

1450 

29-394 

3300 

27-465 

5150 

25-663 

7OOO 

23-9791 

1500 

29-340 

3350 

27-4I5 

5200 

25-616 

7050 

23-935 

1550 

29-286 

3400 

27-364 

5250 

25-569 

7100 

23-891 

1600 

29-233 

3450 

27-3I4 

5300 

25-522 

7150 

23-847 

1650 

29-1/9 

3500 

27-264 

5350 

25-475 

72OO 

23-803 

1700 

29-I26 

3550 

27-214 

5400 

25-428 

7250 

23-760 

1750 

29-072 

3600 

27-164 

5450 

25-382 

7300 

23-716 

I800 

29-OI9 

3650'  27.115 

55oo 

25-335 

7350 

23-673 

1850 

28-966 

3700;  27'065 

:555o 

25-289  Ij  7400 

23-629 

TABLES. 

AIRY'S  TABLE—  Continued. 


169 


Heigh 
in 
feet. 

Aneroid 
or 
Corrected 

Barometer. 

Height 
in 
feet. 

Aneroid 
or 
Corrected 
Barometer. 

Height 
in 
feet. 

Aneroid 
or 
Corrected 
Barometer. 

Height 
in 
feet. 

Aneroid 
or 
Corrected 
Barometer. 

ft. 

in. 

ft. 

in. 

ft. 

in. 

ft. 

1 
in. 

7400 

23-629 

8550 

22-653 

9700 

21-717 

10850 

20-820 

7450 

23-5«6 

8600 

22-611 

9750 

2I-677 

10900 

20-782 

7500 

23-543 

8650 

22-570 

9800 

21-638 

10950 

20-744 

7550 

23-500 

87ooj   22-529 

9850 

21-598 

1  1  oooi    20-706 

7600 

23-457 

8750 

22-487 

9900 

2I'558 

11050 

20-668 

7650 

23-4I4 

8800 

22-446 

9950 

21-519 

IIIOO 

20-630 

7700 

23'37I 

8850 

22-405     10000 

21-479 

11150 

20-592 

7750 

23-328 

8900 

22-364 

IOO5O 

2I-440 

I  1  200 

20-554 

7800 

23-285 

8950 

22-3?3 

IOIOO 

21-401 

II250|     20-5I7 

7850 

23-242 

9000 

22-282 

10150 

21-361 

11300     20-479 

7900 

23-200 

9050 

22-241 

10200 

21-322 

"350 

20-441 

7950 

23-I57 

9100 

22-200 

10250 

21-283 

11400 

20-404 

8OOO 

23-II5 

9150 

22-160  i  10300 

21.244 

1  i  1450 

20-367 

8050 

23.072 

9200 

22-119  !j  10350 

21.205 

11500 

20-329 

8lOO 

23-030 

9250 

22-079 

IO4OO 

2  1  .  1  66 

U550 

20-292 

8150 

22-988 

9300 

22-038    ! 

10450 

21.128 

11600 

20-255 

8200 

22-946 

9350 

21-998    | 

10500 

21.089 

11650!    20-218 

8250 

22-904 

9400 

21-957 

10550 

21.050 

11700 

20-181 

8300 

22-862 

9450 

21-917 

10600 

2I.OI2 

11750 

20-144 

8350 

22-820 

9500 

21-877 

10650 

20.973 

11800 

20-107 

8400 

22-778 

9550 

21-837 

10700 

20.935 

11850 

20-070 

8450 

22-736 

9600 

21-797 

10750 

20.896 

11900     20-033 

8500 

22-695 

9650 

21-757 

10800,    20.858 

11950     19.996 

8550 

22-653 

9700 

21-717 

10850      20.820 

12000;     19.959 

1 70  -THE   ANEROID    BAROMETER. 

MOUNTAIN    ANEROIDS. 

The  majority  of  Mountain  Aneroids  now  have  Airy's  table 
engraved  around  the  dial,  the  circle  bearing  the  scale  of  feet 
being  generally  movable.  This  movable  circle,  as  its  zero  can 
be  turned  to  correspond  with  the  barometer  reading  for  the 
time,  is  convenient  for  approximate  work,  as  the  elevation  can 
be  read  directly  off.  The  barometer  scale,  however,  being  a 
diminishing  one,  this  mode  of  use  would  lead  to  grave  inac- 
curacies. It  is  better,  therefore,  that  the  zero  point  be  set  at 
31  inches  of  pressure  and  the  two  readings  of  feet  subtracted  to 
get  the  difference  in  height. 

TO  USE  THE  ANEROID,  WITH  ALTITUDE  SCALE. 

Find  the  height  in  feet  at  first  station  and  subtract  this  from 
the  height  in  feet  at  second  station.  If  the  mean  temperature 
is  greater  or  less  than  50°  F.,  apply  correction  for  temperature 
as  before  given. 

Example : 

Aneroid  at  Station  A,  1,800  feet.     Thermometer,  50°. 
"       B,      800     "  "  70°. 

The  approximate  height  is  1,000  feet.  The  sum  of  the 
temperature  is  120.  A  correction  of  -^20  is  therefore  applied. 
This  is  20  feet. 

The  difference  of  elevation  is  therefore  i  ,000+20=1 ,020  feet. 

SIZE   OF  THE  ANEROID. 

Aneroids  are  graduated  from  3,000  to  20,000  feet,  from  i^ 
inches  diameter  to  5  inches  diameter.  The  larger  sizes  ^of 
course  permit  the  use  of  more  open  scale,  and  are  consequently 
more  easily  read.  The  smaller  sizes  are,  however,  extremely 
accurate,  and  their  portability  is  a  strong  recommendation. 

POSITION  .OF  THE   ANEROID   IN  USE. 

It  should  be  borne  in  mind  that  all  Aneroids  vary  in  their 
readings  with  the  position  in  which  they  are  held,  reading 
somewhat  higher  in  a  horizontal  position  with  face  up  than 


THE   ANEROID    BAROMETER.  171 

when  vertical.  As  they  are  tested  and  adjusted  in  a  horizontal 
position,  it  is  better  that  they  should  be  uniformly  read  from 
the  horizontal  dial. 

Before  a  reading  is  taken,  the  face  should  be  tapped  slightly 
with  the  finger  to  bring  the  needle  fairly  into  equilibrium. 

ATMOSPHERIC    DISTURBANCE. 

As  there  may  be  considerable  atmospheric  variation  if  any 
great  interval  of  time  elapses  between  two  observations,  engi- 
neers are  now  accustomed  to  use  two  matched  barometers,  one 
of  which  is  kept  in  camp,  where  observations  are  taken  at 
stated  intervals,  whilst  the  other  is  observed  at  corresponding 
times  in  the  field.  A  correction  can  thus  be  applied  for  atmos- 
pheric oscillation.  Where  one  barometer  only  is  used,  observa- 
tions may  be  made  repeatedly  and  the  mean  taken,  or  where  it 
is  inconvenient  to  take  the  higher  elevation  more  than  once, 
the  lower  reading  can  be  taken  after  as  well  as  before  the 
higher,  by  which  method  a  partial  correction  may  be  obtained. 


LOCKE'S  HAND  LEVEL. 


THIS  Instrument  is  made  in  three  form,  brass,  nickel  and 
German  silver.  The  tube  is  6  inches  long,  having,  as 
shown  in  illustration,  the  small  level  on  top  and  near  the 
object  end.  There  is  an  opening  in  the  tube  beneath,  through 
which  the  bubble  can  be  seen, and  is  reflected  by  a  prism  imme- 
diately under  the  level .  Bothends  are  closed  by  disks  of  plain 
glass  to  exclude  the  dust.  There  is  at  the  inner  end  of  the  sliding 
eye-tube  a  semi-circular  convex  lens  which  magnifies  the  level 
bubble  and  the  cross  wires  beneath,  and  allows  the  object  to  be 
clearly  seen  through  the  open  half  of  the  tube.  The  cross  wire 
is  fastened  to  a  small  frame  moving  in  the  level  tube  and  adjusted 
to  its  place  by  the  small  screw  shown  on  the  end  of  the  level  case. 
The  level  of  any  object  in  line  with  the  eye  of  the  observer  is 
determined  by  sighting  upon  it  through  the  tube,  and  bringing 
the  bubble  of  the  level  into  a  position  where  it  is  bisected  by 
the  cross  wire. 


The  Abney  Level  and  Clinometer,  as  show  by  the  above 

illustration,  combines  the  features  of  the  Locke's  Hand  Level, 

with  an  excellent  clinometer.     The  arc  is  divided  to  90  degrees 

each  side  of  zero.     When  the  level  bubble  is  brought  to  the 

172 


LOCKE'S   HAND   LEVEL.  173 

middle,  by  setting  the  vernier  arm  to  zero  on  the  dividing  scale, 
the  bubble  is  seen  through  the  eye  piece  and  the  level  is  ascer- 
tained the  same  as  with  the  Locke's  Level.  As  the  main  tube 
is  square  it  can  be  applied  to  any  surface,  the  inclination  of 
which  is  ascertained  by  bringing  the  level  bubble  into  the 
middle  and  reading  off  the  angle  to  5  minutes  by  the  vernier 
and  arc. 

The  inner  and  shorter  arc  indicates  the  lines  of  different  de- 
grees of  slope,  the  left  hand  end  of  the  vernier  being  applied 
to  the  lines  and  the  bubble  being  brought  into  the  middle  as 
usual. 


THE  ABNEY  LEVEL  WITH  COMPASS. 

The  attachment  of  bar  needle  compass  to  the  regular  Abney 
Level  makes  the  instrument  practically  a  Pocket  Autometer. 
This  instrument  is  sometimes  made  with  Jacob  Staff  Mount- 
ings so  that  it  can  be  used  on  a  staff. 

Directions  for  use  of  Abney  Level  and  Clinometer  and  Abney 
Level  with  Compass  Attachment. 

When  the  height  of  any  object  is  required  to  be  taken,  a 
distance  should  be  correctly  measured  from  the  object,  say  100 
feet,  this  forms  the  base  line,  and  at  which  point  the  observer 
would  stand  ;  then,  direct  his  vision  through  the  tube  of  the 
level  and  elevate  it  until  the  highest  point  of  the  object  is  seen 
bisected  by  the  horizontal  edge  of  the  reflector  within  the  tube. 
While  holding  it  steadily  in  this  position,  the  spirit  level  which 
is  attached  to  the  axis  of  the  arc  should  be  turned  upon  its 
center  until  the  bubble  is  seen  reflected  in  the  mirror,  and  also 
bisected  by  the  horizontal  edge  of  reflector,  the  alignment  is 
then  complete,  and  the  height  of  object  obtained  by  reading  off 
the  index  of  the  arc. 

The  arc  has  two  graduated  scales  upon  it,  one  giving  the 
angular  measurement  by  degrees,  and  subdivided  by  the  vernier 
division  on  the  index.  The  other  scale  is  figured  one  to  ten 
with  their  subdivisions,  representing  T<J->  ^  i>  etc.,  of  the 
length  of  the  measured  base,  and  is  read  off  by  the  fiducial 
edge  at  the  side  of  the  index.  If,  therefore,  the  edge  coin- 
cides with  division  4,  the  height  of  the  object  would  be  ]^  of 
the  base  line,  or  25  feet. 


174  LOCKE'S  HAND  LEVEL. 

In  using  the  Angle  reading  scale  on  arc  the  following  tables 
may  be  referred  to  : 

Angle  i°       gradient  i  in  57.        Angle  12°  gradient  i  in  4.7 

i°  30'       "        i  "   38.  "        14°          "         i   "    4. 

"       2°  i  "   28.6          "        16°         M         i   "    3-4 

11          2°   30'  V  I    "     22.8  "  18°  "  I     "     3. 

"       3°  "        i  "   19.  "       20°         "         i   "    2.7 

"          3°   30'  "  I    "     16.2  "  22°  "  I     "     2.4 

"          4°  "  I    "     14.3  4<  24°  "  I     "     2.2 

•'       4°  30'        <(        i  "    12.6          "        26°          "         i    "    2. 
(<       5°  "        i  "    11.4          <c        28°          "         i    "    1.88 

"       6°  <(        i  «     9-5  "        30°          M         i   "    1-73 

<t          go  w  j    <4        7<J  <t  ^o  c«  j     <i      j    4Q 

"       10°  "  I    {<       5.6  "          40°  4<  I     "     1.20 

45°         "         i   "    i.i 

When  a  slope  or  gradient  is  required  to  be  set  out  to  any 
given  angle,  the  index  of  arc  should  be  set  by  reference  to  the 
above  tables,  and  the  instrument  placed  upon  the  object  to  be 
inclined  ;  this  should  then  be  raised  or  lowered  until  the  bubble 
is  seen  in  the  center  of  spirit  level,  the  required  gradient  beiru^ 
thus  given. 


CHAINS    AND    TAPES. 


THE  ordinary  Gunter's  or  Surveyor's  Chain  consists  of  100 
pieces  of  wire  called  links,  bent  into  rings  at  the  end  and 
connected  one  to  the  other  by  two  rings  and  provided 
with  a  tally  at  the  end  of  every  10  links.     A  link  in  measure- 
ment includes  a  ring  at  each  end  and  is  7.92  long. 

The  iron  chains  are  made  of  Nos.  7,  8  and  9  wire,  varying 
from  •£%  of  an  inch  in  diameter  to  nearly  y%  of  an  inch . 

Steel  chains  are  made  generally  of  No.  12  wire,  which  is 
about  GT  of  an  inch  in  diameter. 

In  the  iron  chains  the  rings  are  oval  and  are  cut  square  so 
that  when  closed  the  danger  of  stretching  apart  and  kinking  is 
greatly  reduced. 

The  steel  chains  are  made  of  the  best  tempered  steel  wire 
with  all  joints,  rings  and  links  brazed  which  prevents  their 
opening  and  allowing  the  chain  to  lengthen. 

The  Engineer's  Chain  is  made  in  the  same  manner  as  the 
Gunter's  or  Surveyor's  Chain  of  both  iron  and  steel  wire,  and 
the  difference  is  that  it  is  100  feet  long,  each  link  being  12 
inches  in  length.  It  is  preferred  to  the  Gunter's  or  Surveyor's 
Chain  on  railroads  or  canal  work  as  it  enables  the  engineer  to 
work  more  rapidly  and  more  accurately. 

In  the  chains,   when  folded  up,  the  links  should   not   be 
parallel  to  each  other,  but  should  be  crossed  at  such  an  angle 
'as  to  cross  each  other  in  the  middle.      This  prevents  the  open- 
ing of  the  links  in  strapping  the  chain  together. 

The  handles  of  all  chains  are  of  brass  and  form  part  of  the 
end  links  to  which  they  are  connected  by  a  short  link  and  jam- 
nut,  by  which  the  length  of  the  chain  is  adjusted. 

The  tallies  also  are  of  brass  and  have  i ,  2 ,  3  or  4  notches  as 
they  mark  10,  20,  30  or  40  feet  from  each  end.  The  5oth  link 
is  marked  by  a  round  tally  to  distinguish  it  from  the  others. 

Chains  are  often  made  with  steel  snaps  in  the  middle  and  at 
one  handle  so  that  the  chain  can  be  separated,  and,  one  handle 
being  removed  and  transferred  to  the  49th  link,  a  chain  of  half 
the  length  is  obtained. 

175 


176  CHAINS   AND   TAPES. 

In  using  the  chain  the  lengths  must  be  taken  from  the  ex- 
treme ends  and  the  marking  pins  placed  on  the  inside  of  the 
handles  ;  it  must  be  drawn  straight  and  taut  and  carefully  ex- 
amined before  each  measurement  is  taken  to  detect  any  kink 
or  other  cause  of  inaccuracy. 

As  all  chains  will  be  lengthened  more  or  less  after  use  in  the 
field,  it  is  advisible  for  the  surveyor  to  carefully  mark  on  a 
level  surface,  where  there  is  no  danger  of  its  being  erased  or 
destroyed,  the  exact  length  of  the  chain  when  new.  By  taking 
this  precaution  a  standard  measure  is  established,  so  that  the 
chain  can  be  adjusted  from  time  to  time  and  always  be  used 
with  perfect  confidence. 

STEEL  TAPES. 

Steel  tapes  are  now  made  in  any  length  up  to  1000  feet  with- 
out joint  from  end  to  end.  The  width  varies  from  ^  of  an 
inch  to  ^  inch,  and  in  thickness  from  i-ioo  to  4-100  of  an 
inch.  For  tapes  of  a  length  not  exceeding  100  feet  the  general 
width  is  ^  of  an  inch  and  2-160  of  an  inch  in  thickness. 

The  three  finishes  generally  preferred  are  the  blued,  nickel- 
plated  and  aluminium  plated.  The  latter  has  the  special  ad- 
vantage of  not  rusting. 

In  tapes  of  over  100  feet  in  length,  the  narrow  steel  ribbon 
is  best  as  it  can  be  dragged  through  brush  or  used  in  all  field 
work  without  danger  of  kinking  or  breaking. 

The  divisions  of  the  tapes  are  generally  marked  in  two  ways, 
viz.:  No.  i,  the  numbers  and  graduation  marks  are  stamped 
on  a  piece  of  brass  which  is  soldered  on  the  top  ;  the  loths  and 
1 2ths  divisions  are  marked  by  single  rivets;  the  i,  5  and  10 
foot  divisions  by  a  brass  strip  which  is  soldered  on  the  top  and 
has  the  numbers  stamped  in  plain  figures.  No.  2,  the  face  of 
the  tape  is  etched  with  acid,  so  that  the  division  marks  and 
figures  stand  out  in  relief ,  while  the  etched  surface  appears  dull. 
Method  No.  2  is  generally  used  in  tapes  of  lengths  not  over 
100  feet,  where  fine  and  accurate  measurements  are  required. 

LINEN  TAPES. 

Accurate  work  cannot  be  done  with  this  form  of  tape  as  it 
will  contract  in  wet  weather  and  expand  in  dry,  and  can  be 
easily  lengthened  by  over-straining.  They  are,  however,  use- 
ful on  inside  work  or  marking  measurements  with  angles,  as 
they  are  pliable  and  can  be  closely  fitted  into  corners. 


CHAINS   AND   TAPES.  177 

METALLIC   TAPES. 

Metallic  Tapes  possess  the  advantage  over  the  ordinary  linen 
tapes  of  having  fine  brass  wire  interwoven  through  their  entire 
length,  and  are  not  liable  to  over-straining,  and  the  danger  of 
contracting  and  expanding  in  wet  or  dry  weather  to  which  the 
linen  tapes  are  subject. 

The  Cases  and  Reels  on  all  tapes  vary  to  such  an  extent  that 
an  accurate  description  would  consume  a  great  deal  of  time 
and  space.  Steel,  linen  and  metallic  tapes  of  100  feet  or  less 
are  generally  put  up  in  leather  and  nickeled  cases  as  it  makes 
them  compact  and  easily  carried  in  the  pocket.  Tapes  of 
greater  length  are  invariably  put  on  reels,  as  they  are  more 
easily  handled,  and  the  reels  being  open  gives  the  tape  a 
chance  to  dry  without. the  danger  of  rusting,  which  so  fre- 
quently occurs  with  the  leather  cases. 


THE  LEVELING  ROD. 


The  Leveling  Rod  is  used  to  measure  the  distance  between 
the  horizontal  line  of  sight  and  the  bench  mark. 

There  are  three  general  classes,  Self- Reading  or  Speaking, 
Target  or  Plain  and  Metric  Rods.  The  Self- Reading  or 
Speaking  Rod  has  a  graduation  such  that  the  point  on  the  rod 
which  lies  in  the  line  of  sight  can  be  easily  read  with  the  teles- 
cope. With  the  self-reading  rod  the  only  duty  of  the  rod 
man  is  to  hold  the  rod  in  a  vertical  position.  The  observer 
notes  and  records  the  readings. 

A  Target  Rod  is  furnished  with  a  sliding  target  which  is 
moved  in  the  plane  of  sight  by  the  rod  man  in  response  to  sig- 
nals from  the  observer  and  the  position  accurately  read  .by 
means  of  a  vernier. 

A  Metric  Rod  is  similar  to  the  Target  Rod,  only  instead  of 
the  graduations  reading  feet  and  decimals  of  a  foot  as  in  the 
above  rods,  the  graduations  are  in  meters  and  centimeters. 


PHILADELPHIA  RODS. 

These  are  made  in  three  forms,  Self-Reading  or  Speaking, 
Target  or  Plain  and  Metric  Rods  as  above  description. 

The  rod  is  made  of  two  strips  of  Spanish  Cedar  each  ^  inch 
thick  by  i^  inches  wide,  and  7  feet  long,  connected  by  two 
metal  collars.  The  upper  one  has  a  clamping  screw  for  hold- 
ing the  two  parts  together  when  the  rod  is  extended  foi  a 
greater  reading  than  7  feet ;  also  is  fitted  with  a  vernier  or 
divided  scale  for  taking  readings  on  the  double  rod. 

Both  sides  of  the  back  strips  and  one  side  of  the  front  are 
recessed  yV  of  an  inch  below  the  edges.  These  depressed  sur- 
faces are  painted  white  and  divided  into  feet,  tenths  and  hun- 
dredths  of  a  foot,  and  the  feet  figured  in  red,  and  tenths  in 
black.  All  the  graduations  and  figures  are  stamped  in  from 
178 


I 


THE    LEVELING   ROD.  179 

steel  dies,  and  hand  painted,  thus  greatly  in- 
creasing their  durability.  All  the  edges  of 
the  rod  and  the  corners  of  the  brass  mount- 
ings are  rounded,  which  makes  the  handling 
^more  comfortable. 

The  front  piece  is  graduated  from  the  bottom 
'upwards  to  7  feet,  and  the  front  surface  of  the 
rear  half  from  7  to  1 3  feet ;  also  from  the  bot- 
tom upwards,  so  that  when  the  rod  is  extended 
to  full  length  it  becomes  a  self- reading  rod  13 
feet  long.  The  back  surface  of  the  rear  half  is 
figured  from  7  to  13  feet,  reading  from  the  top 
down. 

When  used  as  a  target  rod  the  target  carries 
a  scale  (not  a  vernier)  iV  of  a  foot,  being  di- 
vided to  hundredths  and  half-hundredths  of  a 
foot,  by  which  the  rod  is  read  to  half-hun- 
dredths of  a  foot.  In  taking  readings  of  less 
than  7  feet  the  target  is  moved  up  and  down 
the  front  piece,  and  for  readings  greater  than 
7  feet  the  target  is  set  at  7  feet  and  the  back 
piece  is  run  up,  the  readings  being  obtained  by 
a  scale  attached  to  the  upper  collar  of  the^front 
piece. 

When  used  as  a  self- reading  rod  the  loths 
of  feet  are  subdivided  on  the  face  of  the  rod  in- 
to looths.  The  target  then  carries  a  vernier 
graduated  10  spaces,  which  equal  9  on  the  rod, 
so  that  readings  can  be  taken  to  looths  of  a 
foot  by  the  rod  man,  or  if  read  direct,  from  the 
transit,  the  observer  notes  from  the 'telescope 
the  point  of  the  rod  covered  by  the  cross  hair. 


i8o 


THE   LEVELING   ROD. 

NEW  YORK  ROD. 

This  rod  consists  of  two  pieces  of  maple  or 
satinwood  sliding  one  upon  the  other,  the  same 
end  always  held  on  the  ground,  and  the  gradu- 
ations starting  from  that  point. 

The  graduations  are  made  to  tenths  and 
hundredths  of  a  foot,  the  tenth  figures  being 
marked  with  a  black  figure  and  the  feet  with  a 
larger  red  figure.  The  front  piece  carries  a 
target  sliding  in  a  groove.  The  target  has  a 
vernier  so  that  readings  can  be  made  to  thou- 
sandths of  a  foot.  The  front  surface  reads  to 
6.5  feet.  When  a  greater  height  is  required 
the  horizontal  line  of  the  target  is  fixed  at 
6.5  feet,  and  the  upper  half  of  the  rod  carrying 
the  target,  is  run  upward,  and  the  readings  are 
then  obtained  by  a  vernier  on  the  side  of  the 
lower  half  of  the  rod.  When  the  rod  is  ex- 
tended it  is  held  in  place  by  means  of  a  clamp 
at  the  lower  end  of  the  upper  piece. 

This  rod  is  frequently  made  in  three  and 
sometimes  in  four  pieces.  The  special  advan- 
tage of  these  forms  is  that  it  gives  a  rod  of 
greater  length,  at  the  same  time  making  it 
more  compact  and  portable. 

In  both  three  and  four  piece  rods,  the  divis- 
ions, verniers  and  reading  are  the  same  as 
those  on  the  two  part  rod.  The  three  piece 
rod  is  5  feet  long  when  closed  and  14  feet  long 
when  fully  extended.  The  four  piece  rod  when 
closed  is  5  feet  long  and  when  extended  to  its 
full  lengts  is  1 6  feet  long. 


THE   LEVELING   ROD. 


BOSTON    ROD. 

This  rod  is  formed  of  two  pieces  of  mahogany, 
each  about  six  feet  long  and  sliding  easily  by  each 
other  in  either  direction.  One  piece  is  furnished 
with  a  clamp  and  small  vernier  at  each  end  ;  the 
other  or  front  piece  carries  the  target,  and  has  on 
each  edge  an  inlaid  strip  of  satinwood  upon  which 
divisions  of  feet,  tenths  and  hundredths  are 
marked  and  figured. 

The  target  is  a  rectangle  of  wood  fastened  on 
the  front  half,  and  is  painted  red  and  white,  its 
middle  line  being  just  three-tenths  of  a  foot  from 
the  end  of  the  rod.  Each  tenth  of  the  rod  is 
figured  decimally  in  three  figures,  or  to  hun- 
dredths of  a  foot,  and  read  by  the  vernier  to 
thousandths. 

The  target  being  permanent  to  the  rod,  when 
a  reading  of  less  than  six  feet  is  desired,  the  rod 
is  placed  target  end  down,  and  the  piece  carrying 
the  target  is  raised.  When  a  reading  of  more 
than  six  feet  is  desired,  the  rod  is  placed  target 
end  up  and  the  piece  carrying  the  target  is  raised . 
The  reading  being  taken  from  the  other  vernier. 


182 


THE   LEVELING   ROD. 


THE  ARCHITECTS'  ROD. 

This  rod  is  made  of  maple  and  is  very  light.  It 
is  a  simple  sliding  rod  in  two  equal  parts.  When 
closed  it  measures  five  feet  six  inches,  when  ex- 
tended ten  feet. 

There  are  two  forms  of  graduations  used  on  this 
rod.  For  architects  use  the  divisions  are  in  feet, 
inches  and  sixteenths,  and  no  vernier  is  required. 
For  engineers  use  the  front  piece  is  divided  on 
two  sides  to  feet,  tenths  and  hundredths,  reading 
by  verniers  on  the  target  and  side  to  thousandths 
of  a  foot. 

The  target  is  the  same  as  on  the  Philadelphia 
Rod,  and  it  slides  on  the  closed  rod  when  read- 
ings of  less  than  five  and  four-tenths  feet  are  to  be 
taken.  When  a  greater  reading  is  required,  the 
target  is  clamped  at  the  highest  divisions  on  the 
front  half,  the  rod  is  then  run  up  and  the  read- 
ings are  taken  from  the  graduation  on  the  side, 
to  any  point  up  to  ten  feet. 


THE   LEVELING    ROD. 

THE  TELEMETER  ROD. 


This  rod  is  made  of  two  pieces  of  best  straight  grained  white 
pine,  each  three  and  one-half  inches  in  width,  seven-eighths  of 
an  inch  thick  and  six  feet  long.  The  inner  surfaces  of  the  rod 
are  recessed  to  protect  the  divided  surfaces  and  painted  white, 
with  divisions  in  black,  to  feet,  tenths  and  hundred ths  the  feet 
figured  in  red  and  tenths  in  black.  The  two  pieces  are  con- 
nected by  strong  brass  hinges  and  holes  for  transportation. 
When  in  use  they  are  opened  flat  and  jointed  directly  in  line  by 
a  wooden  bar  about  twenty-four  inches  long,  held  to  each  piece 
by  two  strong  brass  thumb  screws  which  enter  into  maple  cen- 
tres screwed  on  each  part  of  the  rod .  When  opened  the  rod  is 
self-reading  and  is  often  used  in  connection -with  stadia  wires 
to  ascertain  distances  by  simple  observation  in  the  same  man- 
ner as  the  Philadelphia  Rod. 


THE  TELESCOPIC  ROD. 


The  rod  is  made  of  maple  and  is  in  three  parts.  The  two 
smaller  upper  parts  slide  out  of  the  larger  lower  part  which 
answers  as  a  case.  When  closed  the  rod  is  five  feet  long  and 
extends  to  fourteen  feet.  It  is  divided  on  recessed  surfaces  to 
feet,  tenths  and  hundredths,  the  divisions  being  painted  and 
figured  like  those  of  the  Philadelphia  Rod. 


THE  CROSS  SECTION  ROD. 


This  rod  is  made  of  well  seasoned  white  pine  and  is  ten  feet 
long,  four  feet  in  middle,  where  there  is  a  an  opening  which 
acts  as  a  handle.  It  tapers  to  both  ends  where  it  is  i^  inches 
square.  Both  sides  are  graduated  on  recessed  white  surfaces, 
the  divisions  being  painted  black  like  those  of  the  Leveling 
Rod,  but  figured  on  each  side  from  reverse  ends.  There  are 
two  adjustable  spirit  levels  mounted,  one  at  each  end. 


1 84 


ROD. 


RANGING  POLKS. 

These  are  made  of  well  seasoned  white  pine  octag- 
onal in  shape,  tapering  from  the  bottom  to  the  top, 
in  lengths  of  6,  8  and  10  feet,  The  bottom  has  a 
steel  shoe,  and  the  graduations  are  in  feet  painted 
red  and  white  alternately.  This  rod  is  also  made 
flat,  about  two  inches  wide  by  one  inch  long  at  the 
bottom,  tapering  at  the  top  where  it  is  one  inch  by 
three-fourths. 

There  is  also  a  convenient  form  of  ranging  pole 
made  of  iron  tubing  eleven-sixteenths  inch  in  diame- 
ter, hung  in  gimbels  so  that  it  can  be  readily  set  from 
a  given  point.  Similar  iron  poles  are  made  without 
gimbels  in  lengths  of  6,  8  and  10  feet  the  same  as 
the  wooden  pole, 


TRIPODS. 


The  three  best  and  most  commonly  used  forms  of  tripods  are 
the  Plain  or  Solid  Leg,  the  Split  Leg  and  the  Extension  or 
Adjustable  Leg. 

The  tripod  heads  on  all  three  forms  are  made  of  the  best  bell 
metal,  and  the  tennons  and  upper  parts  are  cast  in  one  piece 
and  firmly  braced  together. 

The  method  of  attaching  the  instrument  to  the  tripod  head 
varies  according  to  the  construction  of  the  instrument.  The 
two  most  commonly  used  are  the  screw  head  and  the  bevelled 
clamp  head.  In  the  screw  head  the  threads  are  cut  on  the  out- 
side of  the  plate  and  are  deep  and  large,  so  that  the  instrument 
when  tightly  screwed  down  is  very  rigid  and  the  danger  of  the 
threads  stripping  is  avoided.  The  clamp  head,  which  is  the 
quickest  way  of  attaching  the  instrument  to  the  tripod,  consists 
of  three  bevelled  clamps,  one  of  which  is  adjustable.  The  lower 
plate  on  the  transit  is  bevelled  so  that  when  it  is  fitted  in  the 
tripod  head  it  is  only  necessary  to  tighten  the  adjustable  clamp. 


1 86  TRIPODS. 

The  points  or  shoes  consist  of  tapered  brass  ferrules  with  iron 
ends  and  are  firmly  screwed  and  riveted  to  the  wood.  The 
wooden  leg  has  a  slot  at  the  top  which  fits  in  the  lug  cast 
around  the  tripod  head.  There  are  washers  on  the  inside  and 
outside  of  the  slot  part  of  the  tripod  leg  which  prevents  the 
wearing  of  the  woodwork,  A  long  bolt  with  an  anchor  pin 
runs  through  the  woodwork  to  the  tripod  head  lug,  and  is 
tightened  by  a  thumb  screw  and  check  nut  which  prevents  any 
looseness. 

The  Solid  Leg  Tripod  is  made  about  4  feet  8  inches  long 
from  head  to  point  and  tapers  in  each  direction  between  the 
head  and  shoe.  The  diameter  is  about  1 3^"  at  the  swell ;  i  y%" 
at  the  top  and  \Y%"  at  the  point.  This  tripod  is  generally  used 
on  the  heavier  engineer's  transits,  surveyor's  transits  and  Y 
levels. 

The  Improved  Split  Leg  Tripod  is  the  same  as  the  solid  leg 
tripod,  but  has  the  centre  cut  out  which  reduces  the  weight 
and  improves  the  general  appearance.  This  tripod  is  used  on 
the  lighter  Engineering  Transits  and  Levels.  The  increased 
strength  given  by  the  arch  form  compensates  for  the  wood  cut 
out.  The  latest  improved  form  of  split  leg  tripod  is  made  of 
two  strips  of  rounded  wood  firmly  clamped  at  the  top,  centre 
and  point.  This  is  unquestionably  the  strongest  and  most 
rigid  tripod  made. 

The  Extension  Tripod.  The  illustration  shows  the  latest 
improved  form  of  extension  tripod,  and  is  a  decided  improve- 
ment over  the  old  form,  as  it  is  stronger,  more  rigid  and  is 
more  compact  when  closed  for  carrying.  The  construction  of 
the  side  pieces  allows  the  middle  piece,  which  is  round  and 
slides  in  rings,  to  be  clamped  firmly  with  a  single  band  and 
screw.  Slight  changes  in  length  can  be  made  by  releasing  tjie 
clamp  screw  and  twisting  the  middle  piece  up  or  down. 

The  three  best  woods  to  be  used  in  tripods  are  cherry, 
straight  grained  ash  and  white  maple.  The  wood  should  be 
straight  grained  and  thoroughly  seasoned,  so  that  when  it  is 
necessary  for  an  engineer  to  force  the  point  through  rocky  or 
frozen  ground,  in  order  to  secure  a  firm  foundation,  his  entire 
weight  can  be  thrown  on  the  leg  without  danger  of  its  spring- 
ing or  breaking. 


THE  HOUSE  ...OP... 

QUEEN  &  CO.,  Inc. 

Was  established  in  1853  and  REORGANIZED  in  1896, 
and  consists  of  the  following  Sales  Departments  : 

Optical  Department, 

comprising  Optical  and  Ophthalmological  Instruments,  and  Field  and 
Opera  Glasses. 

Mathematical  and  Engineering  Department, 

comprising  Drawing  Instruments  and  Materials,  and  Engineering 
and  Surveying  Instruments. 

Microscopical  Department, 

comprising  Microscopes,  Magnifiers,  and  Botanical  and  Bacteriologi- 
cal Supplies. 

Physical  and  Electrical  Department, 

comprising   Physical   and   Electrical    Instruments    and    Apparatus, 
X-Ray  Apparatus,  and  Anatomical  Models. 

Astronomical  and  Projection  Department, 

comprising    Projection    Apparatus,    Astronomical    Telescopes,   and 
Polarizing  Apparatus. 

Meteorological  Department, 

comprising  Meteorological  Instruments,  Barometers,  and  Thermom- 
eters, and  Pyrometers  for  physical  and  technical  use. 

Photographic  Department, 

comprising  Cameras  and  Lenses  and  Photographic  Supplies  in  general. 
Chemical  Department, 

comprising  Chemicals  and  Chemical  Apparatus,  and  Fine  Balances. 

These  Sales  Departments  depend  principally  upon  our  WELL 
EQUIPPED  FACTORIES,  of  which  we  maintain  the  following: 

Physical,  Electrical  and  Engineering  Instrument  Factory, 

Optical  Factory, 

Thermometer  and  Chemical  Glassware  Factory, 
Electrical  Laboratory,  Wood  Working  Factory. 

Each  of  our  Sales  and  Manufacturing  Departments  is  under  a  compe- 
tent manager,  with  whom  is  associated  an  able  corps  of  assistants,  many 
of  whom  are  recognized  experts  in  their  special  lines. 

In  addition  to  our  own  products,  we  represent  a  number  of  well-known 
foreign  houses  about  whose  apparatus,  which  we  can  supply,  either  from 
stock  or  import  duty  free  for  institutions,  we  are  at  all  times  prepared  to 
give  information. 

CATALOGUE  and  CIRCULARS  of  any  of  the  departments  will  be  sent 
free  by  mail  upon  application. 

QUEEN  &  CO.,  Inc. 

loio  Chestnut  Street 

NEW  YORK  OFFICE,  116  Fulton  Street  PHILADELPHIA 


QUEEN  &  CO..  INC. 

Mathematical 
Instruments  and 
Materials 

...INCLUDING... 

QUEEN,  CROWN,  STAR,  ANCHOR  AND  DIAMOND  BRAND 

INSTRUMENTS,    -    PLANIMETERS,    -    PROTRACTORS, 

SCALES,  -  TRIANGLES,  -  T-SQUARES,  -    DRAWING 

BOARDS,     INKS,    WATER     COLORS,     PENCILS, 

DRAWING,  DETAIL    AND   TRACING    PAPERS, 

ACME   HELIO  BLUE   PRINT  PAPERS,  ETC. 

Engineering 
Instruments  and 
Materials 


...INCLUDING... 


THEODOLITES,  TRANSITS,  LEVELS,  PLANE  TABLES,  COM- 
PASSES, RODS,  POLES,  TAPES,  CHAINS,  CLINQ- 
METERS,  SEXTANTS,  SCIENTIFIC  BOOKS. 

Our  latest  illustrated  catalogues  mailed  to  any  address  on  application. 


101O  Chestnut  Street 

PHILADELPHIA,  PR.,  0.  S.  A. 


The  Quimby 

Railroad  Curve  Projector 
and  Scale 


PATENTED 


THE  QUIMBY  RAILROAD  CURVE  PROJECTOR  and  SCALE 
COMBINES  IN  ONE  ALL  THE  DIFFERENT  CURVES 
REQUIRED  IN  THE  PLOTTING  AND  INVESTIGA- 
TION OF  THE  ALIGNMENT  OF  A  RAILROAD. 
THE  CONSTRUCTION  AND  USEFULNESS  OF  THIS 
VALUABLE  ADDITION  TO  THE  DRAWING  ROOM 
OUTFIT  IS  FULLY  SET  FORTH  IN  THE  FOLLOW- 
ING DIRECTIONS. 

Price,  $15.oo 


QUEEN  &  CO.,  Inc. 

Sole  Manufacturers 

S9  FIFTH  AVENUE  CHESTNUT  STREET 

NEW  YORK 

PHILADELPHIA 


DIRECTIONS 


THE  RAILROAD  CURVE  PROJECTOR 
AND  SCALE 

The  Railroad  Curve  Projector  and  Scale  as  shown  by  FiG.  1,  consist  of  two 
transparent  sheets  of  celluloid  12"x  12"  with  forty-one  different  railroad  curves 
inscribed  on  their  bottom  surfaces;  the  curves  are  laid  off  so  as  to  have  a 
radius  of  each  curve  common  with  one  side  as  shown  in  FIG.  1. 

The  curves  are  all 
carefully  scaled  and  at 
each  half  inch  along 
the  curves  there  is  an 
aperture  which  is  just 
large  enough  to  allow 
the  passing  of  a  pin  or 
pencil  through  the 
sheet,  thus  allowing 
the  points  to  be  trans- 
ferred to  the  plan  on 
which  the  instrument 
is  being  used'. 

The  curves  are 
spaced  along  the  radius 
edge  of  each  sheet  so 
that  the. clamp  which  is 
provided  may  be  used 
while<any  combination 
of  curves  is  being  made.  There  are  apertures  along  the  radius  edges,  as 
shown,  for  use  of  the  clamp. 

'  There  are  forty-one  different  curves  on  each  sheet,  varying  by  15",  and 
running  from  0°-30//  to  10°-30//  for  a  scale  of  V  equals  two  hundred  feet,  or 
varying  by  30"  and  running  from  1°-00//  to  21°-00//for  a  scale  of  \f  equals  one 
hundred  feet. 

The  application  and  facilities  offered  by  the  use  of  this  instrument  will  be 
at  once  apparent  to  the  engineer,  but  its  application  is  explained  fully  in 
connection  with  Figures  2  and  3.  Its  usefulness  in  connection  with  the 
plotting  and  investigation  of  the  alignment  of  a  railroad  is  without  doubt  a 
good  advantage. 

SIMPLE  CURVE  PLOTTING 

FIG.  2,  shows  the  Curve  Projector  as  applied  to  the  plotting  and  fifting 
of  Simple  Curves  to  the  conditions  shown  on  a  contour  map.  It  will  be  noted 
that  the  line  which  has  been  plotted  is  shown  in  this  illustration  by  a  very  heavy 
line  with  the  station  points  all  marked  by  a  dot  and  the  500  ft.  points,  or  every 
fifth  station  by  a  larger  mark  to  the  side  with  the  station  number  near  by. 

The  portion  of  the  line  to  the  point  d  '  may  be  assumed  as  having  been 
plptted.  The  next  step  will  be  to  continue  this  line  so  as  to  fit  the  contours 
ortmlance  the  grading  as  desired.  To  do  this,  take  the  right  hand  sheet  A  as 
required  in  this  case  and  place  it  in  some  position  as  shown  ;  then  take  a 
common  right  angle  triangle  or  the  other  sheet  or  whatever  will  give  a  right 
angle  so  that  the  radius  edge  of  the  Curve  Projector  will  be  held  at  a  right  angle 


to  the  tangent  cd x.  When  this  has  been  done  the  Curve  Projector  may  be 
moved  up  and  down,  always  holding  the  Curve  Projector  against  the  edge  of  the 
triangle.  The  triangle  may  be  held  in  this  position  with  one  hand  or  it  would 
be  well  where  there  is  to  be  much  study  of  the  different  curves  to  have  some 
holes  punched  through  the  triangle  and  put  two  thumb  tacks  through,  this 
will  hold  the  triangle  in  the  proper  position  while  a  full  investigation  may  be 
made  of  the  different  curves.  If  the  point  d  or  P.C.  selected  the  first  time 
does  not  give  the  desired  line,  a  new  position  may  be  selected  and  the  investi- 
gation continued,  and  so  on  until  the  line  is  established. 


When  the  point  d  or  the  P.C.  is  established  also  the  degree  of  the  curve,  it 
remains  to  transfer  the  curve  to  the  paper ;  to  do  this  when  the  even  station 
falls  at  the  P.C.  simply  take  a  pin  or  sharp  pencil  point  and  mark  the  station 
points  through  the  apertures  of  the  Curve  Projector  to  some  station  past 
where  the  P.T.  is  likely  to  fall.  In  case  the  P.C.  does  not  fall  at  an  even 
station  which  is  generally  the  case,  such  as  is  shown  in  this  illustration  at  the 
P.C.  Sta.  184-69.2,  mark  the  P.C.  as  before  also  one  or  two  points  on  the  curve 
then  remove  the  sheet  and  scale  the  position  of  the  first  station,  then  place  the 
sheet  back  in  the  same  position  except  move  it  back  around  the  curve  until 
one  of  the  apertures  fall  over  the  station  just  scaled,  then  while  keeping  the 
curve  passing  through  the  point  marked  out  on  the  curve,  mark  each  station  as 
was  done  in  the  first  case. 

To  locate  the  P.T.  take  the  left  hand  sheet  and  place  in  some  position  as 
shown  by  the  dotted  line,  matching  the  curve  of  the  same  degree  on  the  sheet 
as  has  just  been  put  on  the  paper.  By  moving  the  sheet  back  and  forward 
around  the  curve  on  the  paper  keeping  the  curve  on  the  sheet  always  on  the 
curve  on  the  paper,  then  by  the  use  of  the  triangle  held  with  the  top  edge 
opposite  the  curve  on  the  sheet  which  is  being  plotted  and  the  other  edge 
against  the  radius  edge  of  the  Projector,  the  desired  tangent  ee'  may  be  found. 
The  radius  edge  of  the  sheet  gives  the  position  of  the  P.T. 

To  get  the  scaled  length  of  the  curve  it  simply  remains  to  scale  the  last 
plus  and  count  the  stations  and  to  this  add  the  distance  from  the  P.C.  to  the 
first  station.  With  the  length  of  the  curve  given  and  the  degree  the  central 
angle  may  be  calculated  and  checked  by  intersecting  the  tangents. 

With  the  proper  amount  of  care  the  line  may  be  put  on  the  plan  by  the 
aid  only  of  the  Curve  Projector,  straight  edge,  triangle,  pencil  and  scale,  or 
only  with  the  Curve  Projector,  pencil  and  scale.  Of  course,  to  get  the  notes 
for  the  field  it  would  be  necessary  to  check  up  the  line  as  to  central  angles 
and  pluses. 


COMPOUND  CURVES 

FIG.  3.  This  cut  serves  to  illustrate  the  application  of  the  Curve  Projector 
to  the  plotting  of  compound  curves.  The  illustration  shows  the  full  size 
Curve  Projector  with  both  sheets  but  not  the  full  number  of  curves  which  are 
on  the  Curve  Projector  as  actually  made  for  use. 


Where  the  topography  calls  for  a  compound  curve  it  is  always  more  or  less 
difficult  to  determine  the  degree  of  the  different  branches  of  the  curve  and  the 
point  at  which  the  compound  should  be  made.  The  Curve  Projector  facilitates 
the  work  by  allowing  the  engineer  the  use  of  1640  different  combinations  with 
the  41  different  curves  on  the  two  sheets.  It  also  gives  him  the  opportunity 
of  holding  these  combinations  or  the  two  different  curves  he  is  trying  in  a 
fixed  position  on  the  paper  without  actually  putting  them  on  the  plan,  thus 
saving  a  great  amount  of  erasing  and  work  which  would  have  to  be  done  by  the 
use  of  the  compass  or  common  curves. 

Referring  to  FiG.  3  it  may  be  assumed  that  the  tangent  hh f  has  been 
located  on  the  plan  ;  the  proposition  is  to  locate  a  compound  curve  to  suit  the 
topography  ahead.  If  the  first  branch  of  the  curve  will  be  of  some  considerable 
length  which  would  make  the  location  of  the  first  branch  conform  to  some 
uniform  curve,  it  would  be  well  to  locate  this  branch  in  the  same  manner  as 
described  for  simple  curves,  such  as  the  curve  abb  ' ;  then  by  placing  the  left 
hand  sheet  (in  this  case)  in  some  position  as  shown  so  that  the  curve  on  the 
paper  will  be  directly  under  the  same  degree  curve  on  the  sheet  as  described 
for  locating  a  P.T.;  then  place  the  right  hand  sheet  against  the  left  as  shown  ; 
then  by  sliding  the  right  hand  sheet  up  or  down  until  the  desired  curve  was 
obtained.  If  the  proper  results  could  not  be  obtained  with  the  first  selection 
of  a  P.C.C.  then  the  left  hand  sheet  could  be  moved  back  or  forward  around 
the  curve  abb '  and  some  other  point  of  compound  tried.  When  the  desired 
combination  of  curves  is  secured,  a  tangent  may  be  obtained  as  described  for 
the  simple,  or  if  there  is  another  compound  to  be  made  the  same  method  as  just 
described  may  be  repeated.  In  case  the  two  branches  of  the  curve  are  to  be 
determined  on  at  the  same  time,  it  would  be  best  to  clamp  the  two  sheets 
together  at  different  combinations  and  by  keeping  the  first  curve  always  in 
contact  with  the  tangent  at  some  point  as  a  the  two  curves  may  be  tried  at  the 
same  time  until  the  desired  results  are  obtained.  The  curves  may  be  marked 
on  the  paper  and  scaled  in  the  same  manner  as  described  for  the  simple  curve. 
The  facilities  offered  for  this  kind  of  work  will  at  once  be  apparent  to  the 
engineer. 


19O3 

ueen  &  Co. 


INCORPORATED 


CATALOGUE 


OF 


NQINEERINQ 
INSTRUMENTS 


AND 


MATERIALS 


ioio  Chestnut  St.  and  ion  Sansom  St. 
Philadelphia,  U.  S.  A. 


NEW  YORK  BRANCH 

59  Fifth  Avenue 


Entered  according  to  Act  of  Congress  in  the  year  eighteen  hundred  and  ninety- 
eight  by  Queen  &  Co.,  Incorporated,  in  the  office  of  the  Librarian  of  Congress,  at 
Washington,  D.  C. 


.CATALOGUE, 


OF 


Engineering  instruments 
and  Materials 


REVISED   EDITION 


QUEEN  &  CO.,   INCORPORATED 

ioio  Chestnut  Street 

and  10 1 1  Sansom  Street 


New  York  Office 


PHILADELPHIA,  PA.,  U.  S.  A. 


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ail 


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panies the  order  to  pay  all  express  charges. 

Where  goods  are  bulky,  we  will,  if  customer  so  desires,  ship  by 
freight,  with  sight  draft  attached  to  bill  of  lading,  provided  sufficient 

amount  is  sent  with  order  to  guarantee  freight. 

••*'•'• 
ACCOUNTS.    All  bills  are  due  within  thirty  days  of  their  date,  and  monthly 

accounts  on  the  loth  of  each  month  (without  discount  or  allowance 
for  cash).  Bills  and  accounts  not  promptly  paid  as  above  are  liable 
to  interest. 

REMITTANCES.  The  safest  and  most  economical  method  of  remitting 
money  is  by  Bank  Draft  or  Post  OfLce  Order,  made  payable  to  us. 
Where  neither  of  these  can  be  procured ,  United  States  or  National 
Bank  Notes,  or  Postage  Stamps,  can  be  sent  by  express  with  safety, 
the  sender  prepaying  the  express  charges. 

PACKING.  All  goods  will  be  packed  with  the  utmost  care,  and  purchasers 
must  assume  all  responsibility  for  breakage  and  damage  during  trans- 
portation. We  make  no  charge  for  packing.  Boxes  will  be  charged 
at  cost,  but  we  will  rebate  the  charge  upon  receipt  of  the  packing 
material  used,  provided  it  is  in  good  order  and  express  prepaid. 

SHIPPING.  It  is  usually  advisable  to  make  ordinary  shipments  by  express. 
It  is  a  quick  and  reliable  way,  and  express  companies  are  responsible 
for  damage. 

We  would  suggest  that  to  avoid  correspondence,  our  customers 
allow  us  to  send  their  orders  by  whatever  way  seems  most  practi- 
cable. If  it  is  a  large  shipment,  we  will  send  by  freight  unless  other- 
wise directed.  Mail  packages  will  be  sent  at  the  risk  of  the  pur- 
ohaser,  and  postage  for  same  will  be  charged  for. 


PREFACE. 

We  illustrate  and  describe  in  the  following  pages  a  complete  line  of 
Transits,  Levels  and  their  accessories,  adapted  to  the  use  of  the  Railroad  or 
City  Engineer,  Surveyor,  Architect  or  Builder.  These  instruments  are 
wholly  made  in  our  own  factories,  of  our  own  design,  the  result  of  many 
years 'experience  with  all  kinds  and  makes  of  Engineering  Instruments,  and 
have  had  our  best  efforts  and  personal  supervision.  Unlike  some  other 
makes  of  engineering  instruments,  which  are  sold  at  moderate  prices,  our 
instruments  are  hand -made  and  not  machine  assembled. 

The  exceptionally  low  price  at  which  we  have  been  enabled  to  put 
our  instruments  has  not  resulted  from  any  lowering  of  the  standard  of  work- 
manship, but  from  the  employment  of  labor-saving  tools  of  a  high  order  by 
whichN the  time  of  skilled  workmen  has  been  economized,  thus  enabling  us 
to  produce  instruments  which  we  confidently  assert  are  unsurpassed  by  any 
engineering  instruments  made  in  this  country  to-day,  at  prices  which  are 
far  below  the  prices  of  other  makers  for  the  same  class  of  instruments. 

The  castings  for  the  various  parts  of  the  Transits  and  Levels  are 
made  in  our  own  foundry  from  formulae,  the  result  of  exhaustive  experi- 
ments to  determine  the  best  metal  for  the  several  uses  to  which  the  different 
parts  are  put. 

Our  long  experience  in  optical  work  has  enabled  us  to  achieve  excep- 
tional results  in  the  optical  qualities  of  the  Telescopes  of  our  Transits  and 
Levels,  and  the  highest  power  consistent  with  good  field  and  light  has  been 
secured. 

It  is  to  be  observed  in  this  connection  that  high  power  is  not  alone 
the  most  desirable  quality  in  a  telescope,  and  even  when  high  power  is,  by 
the  finest  possible  optical  combination,  united  with  a  large  field  and  good 
light,  there  are  conditions  where  the  power  of  such  a  telescope  is  a  barrier  to 
its  use,  as  in  foggy  weather,  when  the  fog  itself  is  magnified  in  the  same  ratio 
as  the  object. 

It  follows  from  this,  therefore,  that  on  our  Eastern  coast  and  in  the 
Southern  States,  for  the  greater  portion  of  the  year,  a  telescope  of  compara- 
tively low  power,  but  of  fine  optical  qualities,  can  be  used  on  more  days  and 
with  greater  satisfaction  than  one  of  high  power.  On  the  Western  plains 
telescopes  of  much  higher  power  are  available. 

We  should  be  glad  if  engineers,  in  ordering,  would  state  whether 
they  desire  to  have  a  telescope  with  "  usual  "  or  "  high  "  power. 

Particular  attention  is  directed  to  our  Alt-Azimuth  Instrument, 
High  Grade  Theodolite,  City  and  Bridge  Transits,  Engineers',  Surveyors', 
Solar,  Light  Mountain,  Reconnoissance  and  Builders'  Transits,  Precision 
and  Engineers'  Levels,  Compasses,  Sextants,  etc. 

Our  Engineers'  Aneroids,  compensated  and  specially  tested  and  ad- 
justed for  use  in  engineering,  are  arranged  by  us  to  read  in  absolute  coinci- 
dence with  the  mercurial  column,  and  in  accuracy  of  work  and  non-liability 
to  get  out  of  order  are  unequaled. 

QUEEN  &  CO.,  INCORPORATED. 


INFORMATION  TO  PURCHASERS. 

GUARANTEE. 

All  our  instruments  are  carefully  examined  and  tested  before  ship- 
ment is  made,  and  are  always  in  adjustment  and  ready  for  immediate  use. 
They  are  warranted  perfect  in  all  their  parts,  and  in  the  event  of  any  defect 
appearing  after  reasonable  use,  we  agree  to  repair  or  replace  with  a  new 
part,  or,  if  necessary,  a  new  instrument,  at  once,  and  without  cost,  includ- 
ing transportation  charges.  We  consider  a  defective  instrument  a  much 
greater  injury  to  ourselves  than  to  the  customer. 

INSTRUMENTS   ON   TRIAL. 

For  the  benefit  of  those  unacquainted  with  the  Queen  Instruments 
and  feeling  unwilling  to  purchase  without  first  assuring  themselves  of  the 
accuracy  and  finish  of  the  instrument,  we  will  send,  upon  request,  any  tran- 
sit, level  or  compass  of  our-  make  to  the  nearest  express  station  and  direct 
the  express  agent  to  deliver  the  instrument,  upon  payment  of  our  bill 
together  with  express  charges,  and  hold  the  money  on  deposit  ten  days, 
thus  giving  the  purchaser  time  to  make  an  examination  and  give  it  an  actual 
trial.  If  not  found  as  represented,  the  purchaser  can  return  the  instrument 
within  the  specified  time  and  receive  the  full  amount  paid,  and  direct  the 
instrument  returned  to  us.  This  privilege  applies  only  to  reputable  parties, 
and  is  granted  only  upon  special  request,  and  holds  good  only  within  the 
United  States. 

PACKING   AND   TRANSPORTATION. 

In  shipping  our  instruments  we  in  every  case  carefully  pack  the 
inside  of  the  instrument  box  proper,  with  tissue  paper,  thus  preventing  any 
danger  of  any  part  working  loose.  The  instrument  box  is  then  enclosed  in 
an  outside  packing  box  of  pine,  made  a  trifle  larger  on  all  sides  to  permit 
the  introduction  of  elastic  material,  which  prevents  any  jar  from  affecting 
the  instrument  itself.  In  case  of  foreign  shipment  the  packing  box  is  lined 
with  tin  and  is  hermetically  sealed.  Instruments  can  be  sent  by  express  to 
almost  every  part  of  the  United  States,  Mexico  and  Canada,  as  regular  ex- 
press agents  are  located  at  all  important  points  and  are  forwarded  by  stages 
to  the  smaller  places.  The  charges  are  in  all  cases  paid  by  the  purchaser, 
we  guaranteeing  their  safe  arrival  to  the  express  terminus,  as  we  hold  the 
express  companies  responsible  for  all  losses  and  damage  on  the  way. 

QUEEN    &    CO.'S    ENGINEERING    MANUAL. 

We  publish  a  200  page  Manual  of  Engineering  containing  The  De- 
scription, The  Manipulation,  The  Use,  The  Care  and  The  Adjustments,  etc., 
of  all  Engineering  Instruments.  A  copy  is  furnished  free  of  charge  with 
every  instrument,  or  sent  by  mail  on  receipt  of  25c.  for  paper  bound  ;  $i  .00 
for  cloth  bound. 


SPECIAL  FEATURES 

OF 

THE  ENGINEERING  INSTRUMENTS  MADE  BY 
QUEEN  A,  CO.,   INCORPORATED. 


The  above  illustration  is  a  view  of  the  main  plate  of  the  Queen 
Transits  with  the  standard  removed,  showing  the  position  of  the  verniers, 
plate  levels,  compass  ring,  and  the  way  it  is  graduated,  variation  plate  with 
rack  and  pinion  movement,  opposing  spring  tangent  screw,  to  horizontal 
limb; 

It  will  be  noticed  that  the  verniers  on  our  instruments  are  placed  at 
an  angle  of  35  degrees,  so  that  they  can  be  read  without  stepping  away  from 
the  telescope.  Also,  their  position  is  such  that  they  are  clear  from  all  ob- 
structions and  are  easily  read.  Attention  is  also  called  to  the  graduations 


12  QUEEN   &   CO.,   INC.,   PHILADELPHIA. 

on  the  compass  ring,  which  are  in  quadrants,  o  to  90,  and  are  inclined  in  the 
direction  in  which  they  are  to  be  read. 

The  Telescope  lenses  are  of  special  formulae,  ground  in  our  own 
lense  factory.  The  objective  is  well  connected  and  free  from  spherical  and 
chromatic  aberration.  The  eye-piece  has  four  lenses  ground  with  the 
greatest  accuracy  from  specified  formulae  and  mounted  to  give  the  maximum 
of  power  with  the  largest  flat  field  and  greatest  light. 

The  flagnifying  Power  is  from  twenty  to  twenty-four  diameters, 
but  higher  or  lower  powers  can  be  furnished  if  desired.  The  eye-piece  is 
provided  with  our  patented  screw  focussing  arrangement,  which  adjusts  the 
focus  of  the  cross  wires  in  line  of  collimation  with  precision  and  smooth- 
ness. , 

The  Rack  and  Pinion  movement  to  objective  lens  is  accurately  cut 
and  is  free  from  lost  motion,  so  that  a  sharp  focus  is  obtained.  A  slide  pro- 
tector, or  sleeve  covering,  is  put  on  the  object  slide  of  the  telescope  to  pre- 
vent dirt  and  grit  from  being  carried  into  the  tubes. 

The  Cross  Wires  are  made  of  drawn  platinum  and  of  spider  web. 
The  latter  are  preferable,  as  they  can  be  more  easily  replaced  and  are  not  as 
much  affected  by  atmospheric  changes.  The  telescope  is  well  balanced  and 
reversible  at  both  ends.  The  telescope  axle  is  of  best  Bell  Metal,  having  its 
bearing  ground  in  the  standards. 

The  Arc  is  fitted  and  clamped  to  the  telescope  axle  and  graduated 
into  half  or  third  degrees  with  vernier  reading  to  minutes  or  half  minutes, 
as  the  case  may  be.  A  tangent  screw  is  fitted  to  the  vernier  to  facilitate  the 
reading. 

The  telescope  axle  clamp  is  fitted  on  the  opposite  side  to  the  arc  and 
has  a  spring  box,  which  exerts  an  equal  pressure  on  the  clamp  opposite  the 
tangent  screw. 

The  Vertical  Circle,  when  used,  is  permanently  fixed  to  the  tele- 
scope axle,  and  has  a  vernier  attached  permanently  on  the  standard.  The 
circle  is  graduated  both  ways,  which  is  of  special  advantages  in  back 
sighting. 

The  Spirit  Levels  used  on  our  transits  are  skillfully  ground  and  on 
the  most  scientific  principles.  The  sensitiveness  depends  upon  the  radius 
of  curvature,  and  we  are  prepared  to  supply  any  degree  of  curvature  and, 
consequently,  any  required  degree  of  sensitiveness.  Levels  ground  to  a 
short  radius  give  scarcely  any  displacement  of  the  bubble  for  a  small  varia- 
tion of  the  angle,  while  those  of  sufficiently  long  radius  may  be  made  to 
show  an  appreciable  displacement  of  the  bubble  for  an  angular  value  of  but 
a  fraction  of  second  of  arc.  Before  mounting  the  levels  on  our  instruments 
they  are  carefully  tested  on  an  improved  level  trier  and  must  come  up  to 
the  highest  standard  of  accuracy  for  which  they  are  intended. 

The  Compass  Needle  is  made  of  special  magnet  steel  and  of  such  a 
shape  as  to  retain  great  magnetic  power,  also,  of  proportional  lightness  to 
insure  sensitiveness.  It  swings  on  a  jeweled  centre,  supported  by  a  hard- 
ened and  well-pointed  steel  centre  pin. 


QUEEN  &   CO.,    INC.,   PHILADELPHIA.  13 

The  casting  of  the  Compass  Ring,  as  well  as  all  the  castings  used  in 
our  instruments,  are  of  special  formula  metal  absolutely  free  from  iron. 
The  compass  ring  is  graduated  into  half  degrees  and  figured  in  quadrants. 
It  is  also  slightly  inclined,  which  facilitates  a  much  easier  reading  of  the 
divisions  on  the  edge. 


DOUBLE 
COMPASS 


The  Graduations.  As  shown  in  the  above  illustration,  we  have  four 
systems  of  figuring.  The  compass  circle  is  used  on  the  compass  ring  of  all 
our  instruments,  also,  on  circle  for  horizontal  angles  of  the  Architect 
Levels.  The  plain  circle  is  generally  used  on  Builders'  Transits.  The 
double  compass  circle  is  the  best  for  Reconnoissance,  Surveyors'  and  for 
some  work  on  the  Engineers'  Transits.  The  transit  circle  is  that  used  on 
all  high-grade  engineering  instruments,  unless  otherwise  specified.  The 
last  two  forms  are  recognized  to  be  the  most  satisfactory  figuring,  and  are 
adapted  for  every  form  of  engineering  and  triangulation  work.  . 

The  figures  on  the  horizontal  circle  and  vernier  are  inclined  in  the  di- 
rection they  should  be  read.  The  two  forms  of  graduations  are  used  in  all  our 
Engineering  Instruments.  The  first  is  the  Solid  Silver  Graduation,  which 
means  that  a  strip  of  sterling  silver  is  inlaid  on  the  circle  and  the  gradua- 
tions are  cut  directly  thereon .  The  special  advantage  of  this  form  is  that  the 
graduations  can  always  kept  bright  and  are  easily  read.  It  is  also  possible  to 


14 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


cut  the  very  finest  divisions  on  solid  silver.  The  second  form  is  the  Silvered 
or  Silver- Plated  Graduation.  In  this  the  graduations  are  cut  directly  on  the 
plate,  which  is  then  plated  with  silver.  This  form  is  considerably  less  ex- 
pensive than  the  solid  silver  graduations,  but  it  is  not  advisable  to  cut  the 
divisions  finer  than  third  degrees,  reading  by  vernier  to  half  minutes. 


*/0 


No.  3. 

The  three  divisions  most  commonly  used  are  shown  in  tire  accom- 
panying illustration.  No.  i,  the  horizontal  circle  is  divided  to  half 
degrees  and  reads  by  vernier  to  single  minutes.  No.  2,  the  horizontal 
circle  is  divided  to  one-third  degrees  and  reads  by  vernier  to  30  seconds. 
No.  3,  the  horizontal  circle  is  divided  to  one- third  degrees  and  reads  by  ver- 
nier to  20  seconds. 

The  Plates.  The  top  plate  and  horizontal  circle  are  made  of  special 
rolled  brass,  which  gives  them  uniform  density,  and  the  necessary  hardness 
on  surface  and  edge  for  graduations,  thus  permitting  the  cutter  or  knife  to 
travel  uniformly,  producing  equal  thickness  to  lines  of  graduation.  The 
uniform  density  of  the  metal  also  gives  the  instrument  an  even  expansion 


QUEEN   &   CO.,    INC.,   PHILADELPHIA.  15 

and  contraction  in  extreme  temperature,  and  holds  the  horizontal  circle  and 
vernier  graduations  in  secure  adjustment. 

The  Centres.  Two  forms  of  centres  are  used  on  our  instruments. 
The  first  are  Long  Compound  Centres  made  of  anti-friction  metal.  The 
inner  spindle  is  attached  by  a  large  flange  to  the  vernier  or  upper  plate, 
turning  in  the  outer  socket,  which  is  attached  to  the  horizontal  circle.  The 
action  of  the  centre  clamp  is  entirely  central,  and  when  the  plates  are 
clamped  together  the  whole  instrument  revolves  in  the  socket  of  the  level- 
ing head.  The  centres  are  turned  between  dead  centres  to  insure  the 
greatest  concentricity,  and  will  not  show  any  displacement  of  the  bubble 
when  the  lower  centre  is  revolved.  This  form  is  always  used  on  Municipal, 
Engineers'  and  Light  Mountain  Transits. 

The  second  form  is  the  Combination  or  Half  Long  Centres,  which 
combine  the  great  accuracy  of  the  compound  long  centres  and  possess  the 
advantages  of  the  flat  centres  in  withstanding  rough  handling.  This  form 
is  used  only  on  Surveyors',  Reconnoissance  and  Builders'  Transits. 

The  Leveling  Head  is  made  of  red  metal,  ribbed  castings,  wherein 
lightness  and  strength  are  combined.  The  leveling  screws  have  36  threads 
to  the  inch,  and  are  provided  with  dust-proof  caps  above  and  below  to  pre- 
vent unnecessary  wear  and  injury  by  dust  or  sand.  They  are  fitted  on  the 
lower  end  with  a  ball-jointed  cap,  so  that  the  tripod  plate  will  not  be  sub- 
ject to  unnecessary  wear. 

The  tripod  plate  is  polished,  so  that  when  the  centre  is  shifted  the 
movement  is  perfectly  smooth. 

The  instruments  are  fastened  to  the  tripod  by  two  methods.  The 
first  is  the  Screw  Head.  In  this  there  are  large  and  deep  threads  cut  on  the 
tripod  head  so  that  the  instrument  screws  down  on  the  tripod.  The  second 
is  the  Bevelled  Clamp  Arrangement.  In  this  the  tripod  head  is  cut  on  a 
bevel,  which  fits  in  corresponding  bevelled  clamps  on  the  tripod,  one  of 
which  is  adjustable. 

The  Tangent  Screws  are  in  most  cases  made  of  German  silver,  of 
fine  pitch,  and  free  of  play,  and  in  every  part  of  the  instrument  they  are 
fitted  with  spring  boxes  or  opposing  springs,  so  that  with  a  single  tangent 
screw  both  movements  can  be  made. 

The  instruments  are  packed  in  hardwood  cases,  fitted  with  strong 
leather  carrying  straps ;  also  lock  and  key.  The  bottom  of  the  boxes  are 
provided  with  heavy  rubber  cushions  to  prevent  injury  from  sudden  jars. 
The  packing  inside  of  the  box  is  felt-lined,  so  that  the  instrument  is  no 
danger  of  being  scratched,  and  when  closed  in  the  box  there  is  absolutely 
no  play  in  any  movement.  Snugly  fitted  inside  of  the  box  are  the  plumb 
bob,  magnifying  glass,  screw  drivers,  sunshade  and  adjusting  pins. 


.16 


QUEEN   &   CO  ,    INC.,    PHILADELPHIA. 


cc 


QUEEN"  TRANSIT  THEODOLITE. 


A  147O. 


QUEEN   &   CO.,    INC.,    PHILADELPHIA.  17 


si 


QUEEN"  TRANSIT  THEODOLITE. 


A  1470.  Transit  Theodolite.  Non-repeating  horizontal  circle,  8 
inches  diameter,  graduated  on  solid  silver  in  5  minute  spaces 
reading  by  two  opposite  micrometer  microscopes  to  single 
seconds.  Graduations  are  numbered  at  every  degree.  The 
telescope  objective  has  a  clear  aperture  of  i^  inches  and  18- 
inch  focus.  Inverting  eye-pieces  of  30  and  60  diameters. 
Two  ground  levels  mounted  on  upper  frame  for  approximate 
setting  of  instrument.  Striding  level  is  air  chambered  and 
reads  to  three  seconds  of  arc.  This  instrument  represents 
the  latest  design  of  engineering  instrument.  It  is  constructed 
fc  r  use  in  measuring  horizontal  angles  and  is  especially  adapted 
for  triangulation  where  the  highest  degree  of  accuracy  is 
required.  It  is  our  standard  instrument  for  the  civil  engineer- 
ing departments  of  universities  and  all  triangulation  work. 
This  instrument  is  made  without  compass.  The  upper  part  is 
one  ribbed  casting  mounted  directly  on  the  top  plate.  The 
castings  of  all  parts  are  of  a  special  bronze  and  are  cast  in  one 
mold  to  insure  the  same  density.  The  main  centre  is  extra 
long  and  of  hard  steel.  The  leveling  and  tangent  screws  are 
also  made  of  steel,  and  the  tangent  screws  have  100  threads 
to  the  inch.  Telescope  rests  on  sapphire  bearings  and  the 
clamps  are  constructed  so  as  to  open  easily  to  permit  reversing 
the  telescope  for  straignt  line  measurements.  The  telescope 
is  so  constructed  as  to  permit  illumination  of  the  cross  wires 
by.  lamp.  The  striding  level  rests  on  sapphire  bearings  and 
is  fitted  for  horizontal  and  vertical  adjustment  of  the  telescope 
axis.  The  instrument  is  packed  in  hardwood  case  containing 
sunshade,  screw  drivers,  adjusting  pins,  etc.  Weight  of 
instrument,  36  Ibs.  Price.  $850  oo 


QUEEN   &  CO.,   INC.,   PHILADELPHIA, 


it 


QUEEN"  ALT-AZIMUTH 


A  148O. 


QUEEN   &   CO.,    INC.,    PHILADELPHIA.  19 


cc 


QUEEN  "  ALT-AZIMUTH. 


A  1480.  High  Grade  Alt-Azimuth  as  made  by  us  for  the  United 
States  Government.  Repeating  horizontal  circle  7  inches 
diameter,  graduations  on  solid  silver  in  10  minute  spaces 
reading  by  opposite  double  verniers  to  10  seconds.  Five-inch 
vertical  circle  graduations  on  solid  silver  in  10  minute  spaces 
reading  by  opposite  verniers  to  10  seconds.  Adjustable 
magnifiers  placed  over  verniers  of  horizontal  and  vertical 
circles.  The  telescope  has  a  clear  aperture  of  1^2  inches 
and  a  focus  of  15  inches.  The  eye-piece  is  positive,  of  about 
40  diameters.  The  telescope  axis  is  arranged  so  as  to  permit 
illumination  of  cross  wires  by  lamp.  The  casting  of  the 
telescope  standards  is  made  of  one  piece  in  the  shape  of  a  "U." 
Two  ground  levels  are  mounted  on  top  plate  for  approximate 
leveling.  A  6-inch  ground  and  sensitive  level  is  mounted 
under  telescope.  The  striding  level  is  air  chambered  and 
reads  to  10  seconds  of  arc.  This  instrument  is  made  with 
three  leveling  screws,  without  compass,  and  is  especially 
adapted  for  high  grade  city  work,  also  for  triangulation.  It 
is  packed  in  hardwood  case  containing  sunshade,  plumb  bob, 
screw  driver,  adjusting  pins,  etc.  Weight  of  transit,  24  Ibs.; 
weight  of  tripod,  9  Ibs.  Price,  $550  oo 

A  1481.     High  Grade  Transit  Theodolite,  same  as  No.  A  1480,  but 

made  with  compass  box.  Price,  $600  oo 


20  QUEEN  &  CO.,  IN7C.,  PHILADELPHIA. 

"QUEEN"  CITY  AND  BRIDGE 

COMBINED  TRANSIT  AND  LEVELING 

INSTRUMENT. 


A  1486. 


21 


"QUEEN"  CITY  AND  BRIDGE 
COMBINED  TRANSIT  AND  LEVELING 
.  INSTRUMENT. 

The  City  and  Bridge  Transit,  intended  more  especially  ior  municipal 
work,  represents  the  highest  type  of  engineers'  transit.  No  effort  has  been 
spared  to  make  this  instrument  perfect  in  every  detail.  Optically  it  is  the 
result  of  our  experience  in  the  higher  grades  of  lens  making  and  in  the 
details  of  its  construction,  choice  of  metals  for  the  various  parts  and 
precision  of  workmanship,  it  is  the  result  of  the  cpmbined  efforts  of  a  corps 
of  experts  in  their  several  departments. 

A  1486.  City  and  Bridge  Transit  (for  repeating  angles),  with 
achromatic  terrestrial  telescope  11%  inches  long  with  dust 
cover  to  draw  tube.  •  Object  glass  aperture  IT\  inches;  power 
of  telescope  about  24  diameters;  improved. rack  and  pinion 
movement  to  object  slide  ;  semi-anastigmatic  lens  combination 
to  eye-piece  giving  high  power  without  reducing  the  light  or 
field.  Patent  spiral  screw  focussing  arrangement  to  eye-piece. 
Drawn  platinum  cross  wires  special  adjustable  stadia  hairs. 
Twenty  secoi.us  ground  level  6  inches  long,  mounted  under  tele-* 
scope.  Striding  level  3^  inches  long  suspended  from  vertical 
axu> ;  clamp  and  gradienter  attachment  to  axle  of  telescope. 
Six -inch  vertical  arc  graduated  on  solid  silver  to  ]/?  degrees 
with  adjustable  vernier  reading  to  minutes.  Figuring  of  gradu- 
ations on  arc  o  to  90  each  way  from  centre  line.  Vernier  fitted 
with  adjustable  magnifier.  Five-inch  special  magnet  steel 
needle  swung  on  sapphire  centre,  supported  by  hardened  and 
well  pointed  centre  pin.  Variation  plate  with  improved  clamp 
and  rack  and  pinion  movement.  Horizontal  circle  (graduated 
edge)  6^  inches  in  diameter,  graduated  on  solid  silver  to  }i 
degrees,  with  double  verniers  reading  to  30  seconds.  Figuring 
of  graduations  on  circle  in  two  rows  from  o  to  360  degrees  in 
opposite  directions.  Verniers  fitted  with  patent  adjustable 
magnifiers  and  ground  glass  reflectors ;  clamp  and  opposing 
spring  tangent  to  horizontal  limb  and  centres.  Two  graduated 
right  angle  levels,  one  placed  on  horizontal  circle  and  one  on 
left-hand  standard.  Compound  extra  long  centres  of  special 
formulae  metal  to  reduce  friction.  Special  skeleton  leveling 
plate ;  capped  and  packed  leveling  screws.  Shifting  centre 
tripod  head  ;  split  leg  tripod.  Hardwood  box  containing 
sunshade,  plumb  bob,  screw  driver  and  adjusting  pins.  Weight 
of  transit,  17  Ibs.;  weight  of  tripod,  7  Ibs.  Price,  $300  oo 


22  QUEEN  &  CO.,  INC.,  PHILADELPHIA. 

"QUEEN"  CITY  AND  BRIDGE 

COMBINED  TRANSIT  AND  LEVELING 

INSTRUMENT. 


A  1487. 


QUEEN   &  CO.,   INC.,   PHILADELPHIA.  23 

"QUEEN"  CITY  AND  BRIDGE  TRANSIT. 

A  1487.  City  and  Bridge  Transit  (for  repeating  angles),  with 
achromatic  terrestrial  telescope  ii^  inches  \ong,  with  dust 
cover  to  draw  tube  Object  glass  aperture,  IT%  inches;  power 
of  telescope  about  24  diameters ;  improved  rack  and  pinion 
movement  to  object  slide;  semi-anastigmatic  lens  combination 
to  eye-piece,  giving  high  power  without  reducing  the  light  or 
field.  Patent  spiral  screw  focussing  arrangement  to  eye-piece. 
Special  improved  cross  hairs.  Ten -second  ground  glass  level, 
6  inches  long,  mounted  under  telescope.  Six-inch  vertical  arc, 
graduated  on  solid  silver  to  ^  degrees,  with  adjustable  vernier 
reading  to  minutes.  Figuring  of  graduations  on  arc,  o  to  90 
each  way  from  centre  line.  Clamp  and  gradienter  attachment 
to  axle  of  telescope.  Five-inch  special  magnet  steel  needle, 
swung  on  a  sapphire  centre,  supported  by  hardened  and  well- 
pointed  centre  pin.  Variation  plate,  with  improved  clamp  and 
i  ack  and  pinion  movement .  Horizontal  circle  (graduated  edge) , 
6^  inches  in  diameter,  graduated  on  solid  silver  to  yi  degrees, 
with  double  verniers  reading  to  30  seconds.  Figuring  of  grad- 
uations on  circle,  in  two  rows,  from  o  to  360  degrees  in  opposite 
directions.  Verniers  fitted  with  ground  glass  reflectors ;  clamp 
and  opposing  spring  tangent  to  horizontal  limb  and  centres. 
Two  graduated  right  angle  levels,  one  placed  on  horizontal 
circle  and  one  on  left-hand  standard.  Compound  extra  long 
centres,  of  special  formulae  metal ,  to  reduce  friction.  Special 
skeleton  leveling  plate ;  capped  and  packed  leveling  screws. 
Shifting  centre  tripod  head  :  split  leg  tripod.  Hardwood  box, 
containing  sunshade,  plumb  bob,  screw  driver  and  adjusting 
pins.  Weight  of  transit,  17  Ibs.;  weight  of  tripod,  7  Ibs. 
For  extras,  see  pages  63  to  69.  Price,  $250  oo 

A  1488.  U.  S.  Ordnance  Engineers'  Transit,  as  made  by  Queen  & 
Co.  Horizontal  circle,  6.65  inches  in  diameter,  graduated  on 
solid  silver  to  20  minutes,  opposite  verniers  placed  at  angle  of 
30  degrees  to  telescope.  Verniers,  on  solid  silver,  reading  to 
30  seconds.  Ground  glass  reflectors  over  verniers.  Five-inch 
needle,  with  variation  plate.  Telescope,  10^  inches  long; 
rack  and  pinion  movement  to  objective  lens  ;  revolving  rack 
movement  to  eye-piece.  Special  gradienter  attachment  to 
adjustable  stadia  wires.  Drawn  platinum  cross  wires.  Special 
ground  glass  level  under  telescope.  Vertical  circle,  4^  inches 
in  diameter,  graduated  on  solid  silver,  reading  by  vernier  to 
single  minutes.  German  silver  tangent  screws,  with  deep-cut 
standard  threads.  Semi-anastigmatic  lens  combination  eye- 
piece. All  tangent  screws  fitted  with  spring-box  opposing 
springs.  Extra  long  compound  centres.  Clamp  head,  solid 
leg  tripod.  Hard  wood,  box,  fitted  with  plumb  bob,  sunshade, 
7ernier  glass,  adi«*ting  pins  and  screw  driver.  Price,  $250  oo 


24  QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


"QUEEN"  CITY  AND  BRIDGE  TRANSITS. 


A  1489.     City  and  Bridge  Transit,  same  as  A  1487,  fitted  with  5- 

inch  Vertical  Circle  instead  of  Vertical  Arc.  Price,  $250  o 


A  1490.     City  and  Bridge  Transit,  same  as  A  1487  without  Vertical 

Arc  and  Gradienter  attachment.  Price,  $225  o 

A  1491.     City  and  Bridge  Transit,  same  as  A  1487  without  Vertical 
Arc,  Telescope  Level  and  Clamp  and  Gradienter  attachment. 

Price,  $200  o 

The  level  mounted   under  the  telescope  of  the  City  and 
—          Bridge  Transit  is  extra  large  and  specially  ground  and  the 
sensitiveness  is  equal  to  that  of  most  Wye-levels. 


EXTRAS  FOR  CITY  AND  BRIDGE  TRANSITS. 

Striding  level  3^  inches  long  suspended  from  vertical  axis    .    .    .    .  $25  ex 

Adjustable  Magnifiers  fitted  to  all  Verniers .    .    .  25  oo 

Graduations  on  Horizontal  Circle  reading  to  30" t  •    •  IO  °° 

Graduations  on  Horizontal  Circle  reading  to  20" 20  oo 

Graduations  on  Vertical  Arc  reading  to  30" 5  oo 

Queen  Solar  Attachment 60  oo 

Sights  on  Telescope  with  Folding  Joint 8  oo 

Sights  on  Standards  at  right  angles  to  Telescope 5  oo 

Diagonal  Prism  for  Eye  Piece 8  oo 

Reflector  for  Objective  Glass  of  Telescope  .    ...    .    . 4  oo 

Extension  Tripod  in  place  of  Solid  Leg 10  oo 


QUEEN  &  CO.,  INC.,  PHILADELPHIA.  25 

"QUEEN  "  EXPLORERS'  TRANSIT. 

The  "Queen"  Explorers'  Transit  is  the  smallest  complete  Transit 
made.  It  is  8  inches  high,  the  outer  diameter  of  the  horizontal  limb  is 
4^  inches.  The  Transit  weighs  6  pounds,  Tripod  5  pounds. 

The  Explorers'  Transit  is  of  the  same  grade  and  quality  as  our  City 
and  Bridge  Transit  and  of  corresponding  accuracy. 


A  1492. 

A  1492.  -* Queen"  Explorers' Transit,  with  achromatic  telescope, 
6><?  inches  long,  with  dust  cover  to  draw  tube.  Power  of 
telescope  24  diameters.  Improved  rack  and  pinion  movement 
to  object  slide.  Patent  spiral  screw  focussing  arrangement  to 
eye-piece;  improved  cross  wires;  ground  level,  mounted  under 
.telescope.  2^ -inch  solid  silver  vertical  circle  graduated  to 
y2  degrees  reading  by  vernier  to  single  minutes.  Figuring  of 
graduations  on  circle  from  o  to  90  each  way  from  centre  line. 
Clamp  and  tangent  screw  with  opposing  spring  to  axle  of  tele- 
scope. 2 Y% -inch  special  magnet  steel  needle,  swung  on 
jeweled  centre,  supported  by  a  hardened  and  well-pointed 
centre  pin.  Variation  plate,  with  improved  clamp  and  rack 
and  pinion  movement ;  solid  silver  horizontal  circle  (graduated 
edge)  3>£  inches  in  diameter;  graduated  to.  ^  degrees  with 
double  verniers  reading  to  single  minutes.  Figuring  of  grad- 
uations on  circle,  in  two  rows,  from  o  to  360  degrees  in  op- 
posite directions.  Verniers  fitted  with  ground  glass  reflectors. 
Clamp  and  opposing  spring  tangent  to  horizontal  limb  and 
centres.  Two  graduated  right  angle  levels,  one  placed  on 
horizontal  circle  and  one  on  left  hand  standard.  Compound 
extra  long  centres  of  special  formulae  metal  to  reduce  friction. 
Four  leveling  screws ;  shifting  centre  tripod  head ;  extension 
leg  tripod.  Hardwood  box,  containing  sunshade,  plumb 
bob,  screw  driver  and  adjusting  pins.  Weight  of  transit  6 
pounds;  weight  of  tripods  pounds.  Price,  $220  oo 

Sole  leather  sling  case  for  transit  Price,  $5  oo 

Sole  leather  sling  case  for  tripod  Price,  $3  oo 


26 


QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


QUEEN"  TUNNEL  TRANSIT. 


A  1493 


QUEEN  &  CO.,  INC.,  PHILADELPHIA.  27 


QUEEN"  TUNNEL  TRANSIT. 


The  Tunnel  Transit  is  designed  especially  for  tunnel  or  other  en- 
gineering work  where  the  conditions  are  such  that  the  ordinary  Transit 
cannot  be  used  on  account  of  the  reduced  light.  This  Transit  is  the  result 
of  long  experience  in  making  tunnel  transits,  and  meets  the  requirements 
of  all  work  of  this  class.  The  formula  of  the  Telescope  Lenses  is  such  that 
this  instrument  has  an  amount  of  light  never  before  obtained  in  a  transit 
telescope.  The  Telescope  axis  is  hollow,  and  has  a  special  reflector  for  il- 
luminating the  Cross  Wires.  The  Standards  are  very  wide  so  as  to  secure 
greater  steadiness.  The  Levels  are  long  and  of  large  diameter,  accurately 
ground  and  graduated  on  the  glass.  The  Verniers  are  directly  in  line  with 
the  Telescope,  unusually  large  and  fitted  with  ground  glass  reflectors  and 
adjustable  magnifying  glass. 

A  1493.     "Queen"  Tunnel  Transit,  with  achromatic  telescope  n/2 
inches  long.      Object  Glass  aperture  i  ^  inch.      Power  of  tele- 
scope from  20  to  30  diameters,  as  may  be  ordered.      Dust 
f  Cover  to  draw  tube.       Rack  and  pinion  movement   to  ob- 

[•'  ject   slide.       Spiral    screw    focussing    arrangement    to    eye- 

'<  piece.     Adjustable  Stadia  wires.     Hollow  telescope  axle  and 

reflector  for  illuminating  cross  wires.  20  second  ground  level, 
6  inches  long,  mounted  under  telescope.  Clamp  and  Tangent 
attachment  to  axis  of  telescope.  90  degrees  vertical  arc  with 
vernier  reading  to  single  minutes.  Right  angle  slotted  sight 
mounted  between  standards.  5-inch  needle  with  variation 
vernier.  Horizontal  circle,  (graduated  edge)  6^  inch  in 
diameter,  graduated  on  solid  silver  to  YZ  degrees,  with  double 
verniers  reading  to  30  seconds.  Verniers  in  line  with  tele- 
scope, and  fitted  with  adjustable  magnifying  glass.  Extra 
long  graduated  levels  mounted  at  right  angles  on  the  hor- 
izontal plate.  Clamp  and  tangent  attachment  to  horizontal 
plate  and  centers.  Compound  extra  long  centres.  Capped 
and  packed  leveling  screws.  Shifting  centre  tripod  head. 
Hardwood  box  containing  sun  shade,  plumb  bob,  screw 
drivers  and  adjusting  pins.  Weight  of  transit  16  pounds, 
weight  of  tripod  7  pounds.  Price,  $250  oo 


QUEEN   &   CO.,   INC.,    PHILADELPHIA. 


QUEEN"  FULL  ENGINEERS'  TRANSIT, 


A  1494, 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


"QUEEN"   FULL  ENGINEERS1  TRANSIT. 

The  Full  Engineers'  Transit,  as  designed  and  improved  by  us,  has 
<ong  enjoyed  a  high  reputation  among  engineers.  It  embraces  all  the  usual 
requirements  of  the  Railroad  Engineer,  City  Surveyor  and  Civil  Engineer, 
whose  work  demands  an  accurate  instrument,  easily  manipulated  and  pos- 
sessing the  latest  improvements  known  to  engineering  science.  The 
improved  form  of  compound  long  centres,  giving  the  instrument  great 
accuracy  and  freedom  from  the  probability  of  injury,  and  the  special 
formulae  lens  combination  in  the  telescope,  enabling  the  engineer  to  work 
to  unusual  advantage  under  all  conditions  of  atmosphere,  place  the  Queen 
Engineers'  Transit  in  advance  of  other  instruments  of  its  kind. 

A  1494.  Engineers'  Transit,  with  achromatic  telescope  12  inches 
long,  with  dust  cover  to  draw  tube.  Object  glass  aperture, 
i T\  inches;  power  of  telescope  24  diameters;  improved  rack 
and  pinion  movement  to  object  slide  ;  special  formulae  eye-piece 
lenses,  giving  high  power  without  reducing  the  light  or  field. 
Patent  spiral  screw  focussing  arrangement  to  eye-piece.  Im- 
proved cross  wires.  Twenty-second  ground  level,  6  inches  long, 
mounted  under  telescope.  Six-inch  silvered  vertical  arc  grad- 
uated to  y?  degrees,  with  adjustable  verniers  reading  to  single 
minutes.  Figuring  of  graduations  on  arc  from  o  to  90  each  way 
from  centre  line.  Clamp  and  tangent  screw  with  opposing 
spring  to  axle  of  telescope.  Five-inch  special  magnet  steel 
needle,  swung  on  jeweled  centre,  supported  by  hardened  and 
well -pointed  centre  pin.  Variation  plate,  with  improved  clamp 
and  rack  and  pinion  movement.  Silvered  horizontal  circle 
(graduated  edge)  6^  inches  in  diameter,  graduated  to  ^ 
degrees,  with  double  vernier  reading  to  single  minutes.  Figur- 
ing of  graduations  on  circle,  in  two  rows,  from  o  to  360 
degrees  in  opposite  directions.  Veniers  fitted  with  ground  glass 
reflectors;  clamp  and  opposing  spring  tangent  to  horizontal  limb 
and  centres.  Two  graduated  right  angle  levels,  one  placed  on 
horizontal  circle  and  one  on  left-hand  standard.  Compound 
extra  long  centres  of  special  formulae  metal  to  reduce  friction. 
Special  skeleton  leveling  plate ;  capped  and  packed  leveling 
screws.  Shifting  centre  tripod  head ;  'solid  leg  tripod.  Hard- 
wood box,  containing  sunshade,  plum  bob,  screw  driver  and 
adjusting  pins.  Weight  of  transit,  17  Ibs. ;  weight  of  tripod, 
7  Ibs.  Price.  $185  o< 

A  1495-     Engineers'  Transit,  as  above  in  every  detail,  excepting 

that  the  graduations  are  on  solid  silver.  price,  $210  oo 

For  extras,  see  pages  63  to  6g. 


QUEEN   &  CO.,   INC.,   PHILADELPHIA. 


QUEEN"   ENGINEERS'  TRANSIT. 


A  1496. 


QUEEN   &   CO.,   INC.,   PHILADELPHIA.  31 


QUEEN"   ENGINEERS'  TRANSIT. 


A  1496.  Engineers'  Transit,  with  achromatic  telescope  12  inches 
long,  with  dust  cover  to  draw  tube.  Object  glass  aperture, 
itV  inches.  Power  of  telescope,  24  diameters.  Improved  rack 
and  pinion  movement  to  object  slide.  Special  formulae  eye- 
piece lenses,  giving  high  power  without  reducing  the  light  or 
field.  Patent  spiral  screw  focussing  arrangement  to  eye-piece. 
Improved  cross  wires.  Twenty -second  ground  level,  6  inches 
long,  mounted  under  telescope.  Clamp  and  tangent  screw, 
with  opposing  spring  to  axle  of  telescope.  Five  inch  special 
magnet  steel  needle,  swung  on  jeweled  centre,  supported  by 
hardened  and  well-pointed  centre  pin.  Variation  plate,  with 
improved  clamp  and  rack  and  pinion  movement.  Silvered 
horizontal  circle  (graduated  edge),  6^  inches  in  diameter, 
graduated  to  */&  degrees,  with  double  vernier  reading  to  single 
minutes.  Figuring  of  graduations  on  circle,  in  two  rows,  from 
o  to  360  in  opposite  directions.  Verniers  fitted  with  ground 
glass  reflectors.  Clamp  and  opposing  spring  tangent  to  hori- 
zontal limb  and  centres.  Two  graduated  right  angle  levels, 
one  placed  on  horizontal  circle  and  one  on  left-hand  standard. 
Compound  extra  long  centres,  of  special  formulae  metal,  to 
reduce  friction.  Special  skeleton  leveling  plate.  Capped  and 
packed  leveling  screws.  Shifting  centre  tripod  head.  Solid 
leg  tripod.  Hardwood  box,  containing  sunshade,  plumb  bob, 
screw  driver  and  adjusting  pins.  Weight  of  transit,  17  Ibs. ; 
weight  of  tripod,  7  Ibs.  Price,  $170  oo 

A  1497-     Engineers'  Transit  as  above  in  every  detail,  excepting  that 

the  graduations  are  on  solid  silver.  Price.  $190  oo 

For  extras,  see  pages  63  to  69. 


QUEEN   &   CO.,    INC.,   PHILADELPHIA. 


QUEEN"  PLAIN  ENGINEERS'  TRANSIT. 


A  1498. 


QUEEN   &   CO.,   INC.,    PHILADELPHIA.  33 


QUEEN"  PLAIN   ENGINEERS'  TRANSIT 


A  1498.  Engineers'  Transit,  with  achromatic  telescope  12  inches 
long,  with  dust  cover  to  draw  tube.  Object  glass  aperture, 
ir33  inches.  Power  of  telescope,  24  diameters.  Improved  rack 
and  pinion  movement  to  object  slide.  Special  formulae  eye- 
piece lenses,  giving  high  power  without  reducing  the  light  or 
field.  Patent  spiral  screw  focussing  arrangement  to  eye-piece. 
Improved  cross  wires.  Five-inch  special  magnet  steel  needle, 
swung  on  jeweled  centre,  supported  by  hardened  and  well- 
pointed  centre  pin.  Variation  plate,  with  improved  clamp  and 
rack  and  pinion  movement.  Silvered  horizontal  circle  (gradu- 
ated edge),  6^  inches  in  diameter,  graduated  to  y*  degrees, 
with  double  vernier  reading  to  single  minutes.  Figuring  of 
graduations  on  circle,  in  two  rows,  from  o  to  360  degrees  in 
opposite  directions.  Verniers  fitted  with  ground  glass  reflec- 
tors. Clamp  and  opposing  spring  tangent  to  horizontal  limb 
and  centres.  Two  graduated  right  angle  levels,  one  placed  on 
horizontal  circle  and  one  on  left-hand  standard.  Compound 
extra  long  centres,  of  special  formulae  metal,  to  reduce  friction. 
Special  skeleton  leveling  plate.  Capped  and  packed  leveling 
screws.  Shifting  centre  tripod  head.  Solid  leg  tripod.  Hard- 
wood box,  containing  sunshade,  plumb  bob,  screw  driver  and 
adjusting  pins.  Weight  of  transit.  16  Ibs. ;  weight  of  tripod, 
7  Ibs.  Price,  $150  oo 

A  1499-     Engineers*  Transit  as  above  in  every  detail,  excepting  that 

the  graduations  are  on  solid  silver.  Price,  $170  oo 

For  extras,  see  pages  63  to  60. 


QUEEN   &    CO.,   INC.,   PHILADELPHIA. 


cc 


QUEEN"  SOLAR  ENGINEERS'  TRANSIT. 


A  150O. 


QUEEN  &  CO.,  INC.,   PHILADELPHIA.  JS 


"QUEEN"  SOLAR  ENGINEERS'  TRANSIT. 


A  1500.  The  Engineers'  Solar  Transit  is  the  same  instrument  as 
A  1494,  but  fitted  with  the  Improved  Queen  Solar  Attach- 
ment, which  consists  of  a  small  telescope,  mounted  on  a  hori- 
zontal axis,  which  rests  upon  two  standards  connected  to  a 
circular  base.  This  base  is  the  socket  of  the  so-called  polar 
axis,  and  is  attachable  at  its  lower  extremity  to  the  horizontal 
axis  of  the  telescope.  The  solar  telescope  is  thus  capable  of 
being  turned  on  its  own  horizontal  axis  and  on  its  polar  axis. 
A  small  level  is  applied  parallel  to  the  solar  telescope.  Two 
pointers  are  also  attached  for  use  as  a  specie  of  finder,  the  sun  • 
appearing  in  the  field  of  view  of  the  telescope  when  the  shadow 
of  one  of  these  pointers  is  thrown  on  the  other.  The  solar 
telescope  is  provided  with  a  right  angle  prism  for  conveniently 
observing  the  sun  when  it  is  at  a  considerable  altitude.  It  is 
provided  with  shade  glasses,  for  the  purpose  of  reducing  the 
intensity  of  the  solar  rays  transmitted.  The  small  graduated 
circle  sometimes  attached  to  the  polar  axis  enables  the  hour 
angle  to  be  read  off.  Clamp  and  tangent  are  provided  both  for 
the  vertical  and  for  the  hour  angle  movement.  The  instrument 
is  furnished  with  solid  leg  tripod;  hardwood  box,  containing 
sunshade,  plumb  bob,  screw  driver  and  adjusting  pins.  Weight 
of  transit,  18  Ibs. ;  weight  of  tripod,  7  Ibs.  Price,  $250  oo 

A  1501.     Engineers*  Solar  Transit  as  above  in  every  detail,  except- 
ing that  the  graduations  are  on  solid  silver.  Price,  $275  oo 

For  extras,  see  pages  63  to  69. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


"QUEEN"  FULL  SURVEYORS'  TRANSIT. 


A  1502. 


QUEEN   &   CO.,   INC.,    PHILADELPHIA.  37 


QUEEN"  FULL  SURVEYORS'  TRANSIT. 


The  Surveyors'  Transit,  as  designed  and  improved  by  -us,  is  recog- 
nized to  be  the  best  medium -priced  transit  made,  and  is  especially  adapted 
for  county  surveyors  and  engineers  requiring  an  accurate  and  substantial 
instrument  that  will  stand  rough  handling  in  undeveloped  country,  laying 
out  town  lots,  grading  and  sewerage  work.  The  special  form  of  combina- 
tion centre,  which  possesses  the  advantage  of  the  flat  centres  in  withstanding 
rough  handling,  together  with  the  greater  accuracy  of  the  compound  long 
centres,  is  our  own  special  design  and  gives  the  transit  the  advantage  of 
retaining  the  adjustments  better  than  any  surveyors'  transit  made. 

A  1502.  •«  Queen  "  Surveyors'  Transit,  with  achromatic  telescope 
1 1  inches  long.  Power  of  Telescope  about  24  diameters ; 
improved  rack  and  pinion  movement  to  object  slide : 
straight  draw  focussing  arrangement  to  eye  piece  ;  2c-secoii-. 
ground  level  6  inches  long,  mounted  under  telescope. 
Clamp  and  opposing  spring  tangent  screw  to  axle  of  telescope. 
Five-inch  silvered  vertical  circle,  graduated  to  hnlf  degrees, 
with  fixed  vernier  reading  to  minutes.  Five-inch  special 
magnet  steel  needle,  swung  on  jeweled  centre,  supported  by  a 
hardened  and  well-pointed  centre  pin.  Variation  plate,  with 
improved  clamp.  Silvered  horizontal  circle  (graduated  edge) 
6^6  inches  in  diameter,  graduated  }4  degrees,  with  double 
verniers  reading  to  single  minutes.  Figuring  of  graduations  on 
circle,  in  two  rows,  from  o  to  360  in  opposite  directions. 
Clamp  and  opposing  spring  tangent  to  horizontal  limb  and 
centres.  Two  graduated  right  angle  levels,  one  placed  on 
horizontal  circle  and  one  on  left-hand  standard.  Capped  and 
packed  leveling  screws.  Shifting  centre  tripod  head  :  solid 
leg  tripod  ;  hardwood  box,  containing  sunshade,  plumb  bob, 
screw  driver  and  adjusting  pins.  Weight  of  transit,  15^  Ibs. ; 
wfeight  of  tripod,  7  Ibs.  Price,  $140  <x» 


A  1503.     Surveyors'  Transit,  same  as  above  instrument  in  every 

detail,  excepting  the  graduations  are  on  solid  silver.     Price,  $160  oo 

For  extras,  see  pages  63  to  69. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


cc 


QUEEN"  SURVEYORS'  TRANSIT. 


A  1504. 


QUEEN  &  CO.,   INC.,  PHILADELPHIA. 


'QUEEN"  SURVEYORS'  TRANSfT. 


A  1504.  Surveyors*  Transit,  has  achromatic  telescope  1 1  inches 
long.  Power  of  telescope  about  24  diameters.  Improved 
rack  and  pinion  movement  to  object  slide ;  straight  draw 
focussing  arrangement  to  eye-piece;  2o-second  ground 
level  6  inches  long,  mounted  under  telescope.  Clamp 
and  opposing  spring  tangent  screw  to  axle  of  telescope. 
Five-inch  special  magnet  steel  needle,  swung  on  jeweled 
centre,  supported  by*  a  hardened  and  well-pointed  centre  pin. 
Variation  plate,  with  improved  clamp.  Silvered  horizontal 
circle  (graduated  edge)  6y£  inches  in  diameter,  graduated  to 
YZ  degrees,  with  double  verniers  reading  to  single  minutes. 
Figuring  of  graduations  on  circle,  in  two  rows,  from  o  to  360 
in  opposite  directions.  Clamp  and  opposing  spring  tangent 
to  horizontal  limb  and  centres.  Two  graduated  right  angle 
levels,  one  placed  on  horizontal  circle  and  one  on  left-hand 
standard.  Capped  and  packed  leveling  screws.  Shifting 
centre  tripod  head  ;  solid  leg  tripod  ;  hardwood  box,  contain- 
ing sunshade,  plumb  bob,  screw  driver  and  adjusting  pins. 
Weight  of  transit,  15  Ibs.  ;  weight  of  tripod,  7  Ibs.  Price,  $130  oo 


A  1505.    Surveyors'  Transit,  same  as  above  in  every  detail,  except- 
ing that  the  graduations  are  on  solid  silver.  Price,  $150  oc 

For  extras,  see  pages  63  to  69. 


QUEEN  &  CO.,  INC.,  PHILADELPHIA. 

QUEEN"  SOLAR  SURVEYORS'  TRANSIT. 


A  1506 


QEEEN   &   CO.,   INC.,    PHILADELPHIA.  4J 


"QUEEN"  SOLAR  SURVEYORS'  TRANSIT. 


A  1506.  The  Surveyors'  Solar  Transit  is  the  same  instrument  as 
A  1502,  but  fitted  with  the  Improved  Queen  Solar  Attach- 
ment, which  consists  of  a  small  telescope  mounted  on  a  hori- 
zontal axis,  which  rests  upon  two  standards  connected  to  a  cir- 
cular base.  This  base  is  the  socket  of  the  so-called  Polar 
Axis,  and  is  attachable  at  its  lower  extremity  to  the  horizontal 
axis  of  the  telescope.  The  Solar  Telescope  is  thus  capable  of 
being  turned  on  its  own  horizontal  axis  and  on  its  polar  axis. 
A  small  level  is  applied  parallel  to  the  Solar  Telescope.  Two 
pointers  are  also  attached  for  use  as  a  specie  of  finder,  the  sun 
appearing  in  the  field  of  view  of  the  telescope  when  the  shadow 
of  one  of  these  pointers  is  thrown  on  the  other.  The  Solar 
Telescope  is  provided  with  a  right  angle  prism  for  conveniently 
observing  the  sun  when  it  is  at  a  considerable  altitude  It  is 
provided  with  shade  glasses  for  the  purpose  of  reducing  the 
intensity  of  the  solar  rays  transmitted.  The  small  graduated 
circle  sometimes  attached  to  the  polar  axis  enables  the  hour 
angle  to  be  read  off.  Clamp  and  tangent  are  provided  both  for 
the  vertical  and  for  the  hour  angle  movement.  The  instru- 
•  nient  is  furnished  with  solid  leg  tripod ;  hardwood  box,  con- 
taining sunshade,  plumb  bob,  screw  driver  and  adjusting  pins. 
Weight  of  transit,  16%  Ibs.  ;  weight  of  tripod,  7  Ibs.  Price,  $200  oo 

A  1507.  .  Surveyors*  Solar  Transit,  as  above  in  every  detail,  except- 
ing that  the  graduations  are  on  solid  silver.  Price,  $225  oo 

For  extras,  see  pages  63  to  69. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA.. 

"QUEEN"  LIGHT  MOUNTAIN  OR  MINING 

TRANSIT. 


A  1508. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA.  43 

"QUEEN"  LIGHT  MOUNTAIN  OR  MINING 
TRANSIT. 

The  Light  Mountain  Transit,  as  introduced  by  us,  meets  every 
demand  for  a  light  transit — possessing  great  accuracy — for  use  in  the  moun- 
tains or  underground  mining  work.  It  is  constructed  on  the  same  model, 
of  the  same  material  and  workmanship  as  our  Engineers'  Transit,  and 
differs  from  it  only  in  reduced  size  and,  consequently,  lightness  of  construc- 
tion, thus  making  it  extremely  portable.  When  packed  in  our  sole  leathex 
case,  with  shoulder  or  saddle  straps,  it  can  be  carried  as  easily  as  a  knap 
sack,  and  enables  the  engineer  to  work  and  travel  rapidly  and  with  great 
ease. 

A  1508.  Light  Mountain  Transit,  with  achromatic  telescope  9 
inches  long,  with  dust  cover  to  draw  tube.  Power  of  telescope 
24  diameters.  Improved  rack  and  pinion  movement  to  object 
slide;  special  formulae  eye-piece  lenses,  giving  high  power 
without  reducing  the  light  or  field  ;  patent  spiral  screw  focus- 
sing arrangement  to  eye-piece ;  improved  cross  wires.  Ten- 
second  ground  level,  mounted  under  telescope.  Four-inch 
silvered  vertical  arc  graduated  to  ^  degrees  reading  by  adjust- 
able verniers  to  single  minutes.  Figuring  of  graduations  on 
arc  from  oto  go  each  way  from  centre  line.  Clamp  and  tan- 
gent screw  with  opposing  spring  to  axle  of  telescope.  Four- 
inch  special  magnet  steel  needle,  swung  on  jeweled  centre, 
supported  by  a  hardened  and  well -pointed  centre  pin.  Varia- 
tion plate,  with  improved  clamp  and  rack  and  pinion  movement  ; 
silvered  horizontal  circle  (graduated  edge)  5^  inches  in  diam- 
eter ;  graduated  to  ^  degrees  with  double  verniers  reading  to 
single  minutes.  Figuring  of  graduations  on  circle,  in  two  rows, 
from  o  to  360  degrees  in  opposite  directions.  Verniers  fitted 
with  grout:!  glass  reflectors.  Clamp  and  opposing  spring 
tangent  to  1  orizontal  limb  and  centres.  Two  graduated  right 
angle  levels,  one  placed  on  horizontal  circle  and  one  on  left- 
hand  standard.  Compound  extra  long  centres  of  special  for- 
mulae metal  to  reduce  friction.  Special  skeleton  leveling 
plate.  Capped  and  packed  leveling  screws ;  shifting  centre 
tripod  head  ;  extension  leg  tripod.  Hardwood  box,  containing 
sunshade,  plumb  bob,  screw  driver  and  adjusting  pins. 
Weight  of  transit,  10  Ibs.  ;  weight  of  tripod,  6  Ibs.  Price,  $185  oo 

A  1509.  Light  Mountain  Transit,  as  above  in  every  detail,  except- 
ing that  the  graduations  are  on  solid  silver.  Price,  $210  oo 

For  extras,  see  pages  63  to  69. 


QUEEN   £   CO.,   INC.,   PHILADELPHIA. 


QUEEN"  LIGHT  MOUNTAIN   OR  MINING 
TRANSIT. 


A  151O. 


QUEEN   &   CO.,   INC.,   PHILADELPHIA.  45 


"QUEEN"  LIGHT  MOUNTAIN  OR  MINING 
TRANSIT. 

A  1510.  Light  Mountain  Transit,  with  achromatic  telescope  9 
inches  long,  with  dust  cover  to.  draw  tube.  Power  of  tele- 
scope 24  diameters.  Improved  rack  and  pinion  movement  to 
object  slide ;  special  formulae  eye-piece  lenses,  giving  high 
power  without  reducing  the  light  or  field;  patent  spiral 
screw  focussing  arrangement  to  eye-piece ;  improved  cross 
wires.  Ten-second  ground  level,  mounted  under  telescope. 
Clamp  and  tangent  screw  with  opposing  spring  to  axle  of  tele- 
scope. Four-inch  special  magnet  steel  needle,  swung  on 
jeweled  centre,  supported  by  a  hardened  and  well-pointed 
centre  pin.  Variation  plate,  with  improved  clamp  and  rack 
and  pinion  movement;  silvered  horizontal  circle  (graduated 
edge)  5^2  inches  in  diameter,  graduated  to  y£  degrees  with 
double  verniers  reading  to  single  minutes.  Figuring  of  grad- 
ations on  circle,  in  two  rows,  from  o  to  360  degrees  in  oppo- 
site directions.  Verniers  fitted  with  ground  glass  reflectors. 
Clamp  and  opposing  spring  tangent  to  horizontal  limb  and 
centres.  Two  graduated  right  angle  levels,  one  placed  on 
horizontal  circle  and  one  on  left-hand  standard.  Compound 
extra  long  centres  of  special  formulae  metal  to  reduce  friction. 
Special  skeleton  leveling  plate.  Capped  and  packed  leveling 
screws;  shifting  centre  tripod  head;  extension  leg  tripod. 
Hardwood  box,  containing  sunshade,  plumb  bob ,  screw  driver 
and  adjusting  pins.  Weight  of  transit,  10  Ibs.  ;  weight  of 
tripod,  6  Ibs.  Price,  $170  oo 

A  1511.  Light  fountain  Transit,  as  above  in  every  detail,  except- 
ing that  the  graduations  are  on  solid  silver.  Price,  $190  oo 

For  extras,  see  pages  63  to  69. 


^6  QUEEN  &  CO.,    INC.,   PHILADELPHIA. 

"QUEEN"   LIGHT  MOUNTAIN   SOLAR  TRANSIT. 


A  1512. 


QUEEN   &  CO.,   INC.,    PHILADELPHIA.  47 


•  i 


QUEEN"  LIGHT  MOUNTAIN  SOLAR  TRANSIT. 


A  1512.  The  Light  Mountain  Solar  Transit  is  the  same  instrument 
as  A  1508,  but  fitted  with  the  Improved  Queen  Solar  Attach- 
ment, which  consists  of  a  small  telescope  mounted  on  a  hori- 
zontal axis,  which  rests  upon  two  standards  connected  to  a 
circular  base.  This  base  is  the  socket  of  the  so-called  polar 
axis,  and  is  attachable  at  its  lower  extremity  to  the  horizontal 
axis  of  the  telescope.  The  solar  telescope  is  thus  capable  of 
being  turned  on  its  own  horizontal  axis  and  on  its  polar  axis, 
A  small  level  is  applied  parallel  to  the  solar  telescope.  Two 
pointers  are  also  attached  for  use  as  a  specie  of  finder,  the  sun 
appearing  the  field  of  view  of  the  telescope  when  the  shadow 
of  one  of  these  pointers  is  thrown  on  the  other.  The  solar 
telescope  is  provided  with  a  right  angle  prism  for  conven- 
iently observing  the  sun  when  it  is  at  a  considerable  altitude. 
It  is  provided  with  shade  glasses  for  the  purpose  of  reducing 
the  intensity  of  the  solar  rays  transmitted.  The  small  gradu- 
ated  circle  sometimes  attached  to  the  polar  axis  enables  the 
hour  angle  to  be  read  off.  Clamp  and  tangent  are  provided 
both  for  the  vertical  and  for  the  hour  angle  movement.  This 
instrument  is  furnished  with  solid  leg  tripod  ;  hardwood  box, 
containing  sunshade,  plumb  bob,  screw  driver  and  adjusting 
pins.  Weight  of  transit,  n  Ibs.  ;  weight  of  tripod,  6  Ibs. 

Price,  $250  oo 

A  1513.     Light  Mountain  Solar  Transit,  as  above  in  every  detail, 

excepting  that  the  graduations  are  on  solid  silver.         Price,  $275  oo 

For  extras,  see  pages  63  to  69. 


S  QUEEN  &   CO.,   INC.,   PHILADELPHIA. 

"QUEEN"   LIGHT  MOUNTAIN  TOP  TELESCOPE 

TRANSIT. 


QUEEN   &   CO.,    INC.,    PHILADELPHIA.  49 

"QUEEN"   LIGHT  MOUNTAIN  TOP  TELESCOPE 

TRANSIT. 

A  1514.  Light  Mountain  Transit,  same  as  A  1508,  but  fitted  with 
detachable  top.  telescope  for  vertical  sighting.  This  top  tele- 
scope is  made  so  that  it  can  be  readily  attached  to  the  main 
telescope,  and  is  connected  with  the  main  telescope  by  coupler 
nuts  which  fasten  it  securely  over  the  centre  of  the  instrument. 
This  telescope  is  adjusted  to  the  main  telescope  of  the  transit 
so  that  the  line  of  collimation  of  both  are  parallel  and  in  the 
same  plane.  A  diagonal  prism  is  often  used  with  the  extra 
telescope  for  greater  convenience  in  sighting .  Telescope  length , 
7  inches ;  magnifying  power  of  24  diameters.  Rack  and  pinion 
movement  to  object  glass.  Patent  spiral  screw  focussing 
arrangement  to  eye-piece.  Improved  cross  wires.  The  instru- 
ment is  furnished  with  extension  leg  tripod ;  hardwood  box, 
containing  sunshade,  plumb  bob,  screw  driver  and  adjusting 
pins.  Weight  of  transit,  n  Ibs. ;  weight  of  tripod,  6  Ibs. 

Price,  $210  oo 

A  1515.     Light  Mountain  Transit  as  above  in  every  detail,  excepting 

that  the  graduations  are  on  solid  silver.  Price,  $235  oo 

A  1516.  Light  Mountain  Transit,  same  as  A  1508,  but  fitted  with 
the  improvd  detachable  side  telescope  for  vertical  sighting. 
This  extra  telescope  is  fitted  by  a  flange  and  disk  connecting 
it  with  the  axis  so  as  to  make  it  exactly  parallel  with  the  main 
telescope.  Counterpoise  is  fitted  to  the  other  end  of  axis,  and 
both  can  be  detached  at  pleasure.  The  extra  side  telescope 
swings  over  the  outside  of  the  transit  plate.  A  diagonal  prism 
is  often  used  with  the  extra  telescope  for  greater  convenience 
in  sighting.  Telescope  length,  7  inches;  magnifying  power  of 
24.  diameters.  Rack  and  pinion  movement  to  object  glass. 
Patent  spiral  screw  focussing  arrangement  to  eye-piece.  Im- 
proved cross  wires.  The  instrument  is  furnished  with  exten- 
sion leg  tripod ;  hardwood  box,  containing  sunshade,  plumb 
bob,  screw  driver  and  adjusting  pins.  Weight  of  transit,  n 
Ibs. ;  weight  of  tripod,  6  Ibs.  Price,  $210  oo 

A  1517.     Light  Mountain  Transit  as  above  in  every  detail,  excepting 

that  the  graduations  are  on  solid  silver.  Price,  $235  oo 

For  extras,  see  pages  63  to  69. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


1C 


QUEEN"   RECONNOISSANCE  TRANSIT. 


A  1520. 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


"QUEEN"  RECONNOISSANCE  TRANSIT. 

A  1518.  The  Reconnoissance  Transit,  as  recently  designed  by  us,  is 
in  response  to  a  demand  for  a  light  transit  for  rapid  work  wrhere 
extreme  accuracy  is  not  required.  It  has  an  8-inch  achromatic 
telescope  with  fine  optical  power,  large  field  and  abundance  of 
light;  improved  stadia  wires;  4^ -inch  ground  level  under 
telescope;  3^ -inch  vertical  circle,  with  fixed  vernier  reading 
to  5  minutes  ;  clamp  and  tangent  screw  to  axis  of  telescope ; 
3^ -inch  bar  needle,  with  agate  centre.  Compass  circle  fitted 
with  variation  plate.  Horizontal  circle,  5^2  inches  in  diameter, 
graduated  in  half  degrees  reading  by  one  vernier  to  single  min- 
utes. Leveling  head  and  shifting  centre.  Light  extension 
tripod.  Hardwood.box  fitted  with  reading  glass,  plumb  bob, 
screw  driver,  adjusting  pins  and  rubber  cover.  Weight  of 
instrument,  8  Ibs. ;  complete  weight  with  tripod,  15  Ibs. 
Reconnoissance  Transit,  as  above,  Price,  $125  oo 

A  1519.     Reconnoissance  Transit,  with  shifting  centre,  without  stadia 

wires,  with  solid  leg  tripod  instead  of  extension.  Price,  $110  oo 

A  1520.     Reconnoissance  Transit,  without  shifting  centre  and  stadia 

wires ;  with  solid  leg  tripod  instead  of  extension.          Price,  $100  oo 

For  extras,  see  pages  63  to  69. 


QUEEN    &   CO.,   INC.,    PHILADELPHIA. 


"QUEEN"   BUILDERS'  TRANSIT* 


A  1521. 


QUEEN   &   CO.,   INC.,   PHILADELPHIA.  53 


"QUEEN"  BUILDERS1  TRANSIT. 


A  1521.  The  Builders'  Transit  fills  a  long  felt  want  among  archi- 
tects and  builders,  as  it  is  often  desirable  to  determine  a  point 
in  a  vertical  plane  above  or  below  the  object  observed,  or  points 

on  either  side  and  in  line  of  the  centre  of  the  instrument.    The 

• 

construction  is  compact,  light  and  well  adapted  for  all  work  of 
architects  and  builders.  It  has  an  8-inch  achromatic  telescope 
with  fine  optical  power,  large  field  and  abundance  of  light ; 
improved  cross  wires  ;  4}^ -inch  ground  level  under  telescope  ; 
3^-inch  vertical  circle,  wjth  fixed  vernier  reading  to  5  min- 
utes ;  clamp  and  tangent  screw  to  axis  of  telescope.  Hori- 
zontal circle,  5^  inches  in  diameter,  graduated  in  half  degrees 
reading  by  vernier  to  single  minutes.  Light  solid  leg  tripod. 
Hardwood  box  fitted  with  reading  glass,  plumb  bob,  screw 
driver,  adjusting  pins  and  rubber  cover.  Weight  of  instru- 
ment, 7  Ibs. ;  weight  complete  with  tripod,  14  Ibs. 
Builders'  Transit,  as  above,  Price,  $90  oo 

A  1521^.     Builders'  Transit,  same  as  A  1521,  but  without  vertical 

circle.  Price,  $80  oo 


54 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


1C 


QUEEN"  PLANE  TABLES. 


A  1522.   , 

A  1522.  Plane  Table  for  Topographical  Work.  With  Alidade  and 
astronomical  telescope  n  inches  long,  with  stadia;  4}^ -inch 
vertical  circle  on  silver  to  i  minute;  level  on  telescope,  clamp 
and  tangent  on  column.  Power  of  telescope,  24  diameters. 
Brass  compass,  5x5  inches  base  ;  2^ -inch  needle  fitted  with 
stop.  Compass  ring  raised  and  divided  to  ^  degrees.  Com- 
pass base  fitted  with  two  graduated  bubbles.  Drawing  board, 
24x30  inches,  of  improved  construction.  Substantial  split 
leg  tripod,  fitted  with  latest  improved  three  leveling  screw 
arrangement.  The  centre  supporting  the  board  revolves  in  a 
metal  groove  provided  with  clamp  and  tangent  screws  with 
opposing  spring.  Instrument  complete  in  polished  box  con- 
taining plumb  bob,  arm  for  plumb  bob,  paper  clamps,  etc. 

Price,  $200  oo 


QUEEN  &  CO.,   INC.,   PHILADELPHIA.  55 


A  1523.  Plane  Table  for  Topographical  Work,  with  Alidade  and 
astromical  telescope  9  inches  long,  with  stadia,  4^ -inch  ver- 
tical circle  on  silver  to  5  minutes ;  level  on  telescope,  clamp 
and  tangent  on  column.  Power  of  telescope  20  diameters. 
Brass  compass  5x5  inch  base,  2^ -inch  needle,  fitted  with 
stop.  Compass  ring  raised  and  divided  to  ^  degrees.  Com- 
pass base  fitted  with  two  graduated  bubbles.  Drawing  board 
24  x  30  inches,  of  improved  construction .  Substantial  split  leg 
tripod,  fitted  with  latest  improved  three  leveling  screw  arrange- 
ment. The  centre  supporting  the  board  revolves  in  a  metal 
groove.  Instrument  complete,  in  polished  box,  containing 
plumb  bob,  arm  for  plumb  bob,  paper  clamps,  etc.  Price,  $150  oo 

A  1524.  Plane  Table  for  Topographical  Work,  with  Alidade  and 
telescopic  sights,  with  stadia,  4 y^ -inch  vertical  circle  on  silver 
to  5  minutes,  clamp  and  tangent  on  column.  Brass  compass 
5x5  inch  base,  2  24 -inch  needle,  fitted  with  stop.  Compass 
ring  raised  and  divided  to  ^  degrees.  Compass  base  fitted 
with  two  graduated  bubbles.  Drawing  board  24  x  30  inches, 
of  improved  construction.  Substantial  split  leg  tripod,  fitted 
with  latest  improved  three  leveling  screw  arrangement.  The 
centre  supporting  the  board  revolves  in  a  metal  groove. 
Instrument  complete,  in  polished  box,  containing  plumb  bob, 
arm  for  plumb  bob,  paper  clamps,  etc.  Price,  $125  oo 

A  1525.  Plane  Table  for  Topographical  Work,  with  Alidade  and 
compass  sights.  Brass  compass  5x5  inch  base:  2^ -inch 
needle,  fitted  with  stop.  Compass  ring  raised  and  divided  to 
YZ  degrees.  Compass  base  fitted  with  two  graduated  bubbles. 
Drawing  board  24  x  30  inches,  of  improved  construction. 
Substantial  split  leg  tripod,  fitted  with  latest  improved  three 
leveling  screw  arrangement.  The  centre  supporting  the  board 
revolves  in  a  metal  groove.  Instrument  complete,  in  polished 
box,  containing  plumb  bob,  arm  for  plumb  bob,  paper  clamps, 
etc.  Price,  $100  oo 


QUEEN   &  CO.,    INC.,   PHILADELPHIA. 


cc 


QUEEN"   PRECISION   LEVEL. 


A  1526. 


QUEEN   &   CO.,    INC.,    PHILADELPHIA.  57 


"QUEEN"   PRECISION  LEVEL. 

A  1526.  The  Queen  Level  of  Precision,  is  built  for  the  most  exact 
work  and  can  be  used  on  the  highest  grades  of  leveling.  The  tel- 
escope objective  has  an  aperture  of  i  ^4  inches  diameter,  1 6-inch 
focus,  with  two  astronomical  eye-pieces  magnifying  to  40  or  60 
diameters.  The  telescope  collars  are  supported  in  Y's  and  rest 
on  highly-polished  slightly-curved  sapphire  blocks,  which  are 
firmly  set  in  the  Y's.  The  Y's  are  connected  by  a  strong  rod, 
and  one  Y  hinges  on  a  bar  between  hardened  steel  pivots  and 
the  other  is  adjustable  by  a  graduated  micrometer  screw  in 
azimuth,  which  can  be  used  to  read  five  seconds  of  arc  of  ele- 
vation and  inclination,  and  with  it  the  finest  grades  can  be 
positively  measured,  as  well  as  the  true  horizontal  line  estab- 
lished. The  striding  level  has  an  air  chamber,  and  one  divi- 
sion equals  3  seconds  of  arc.  The  reflecting  mirror  enables 
the  readings  to  be  taken  without  the  observer  changing  his 
position.  The  telescope  collar  is  provided  with  a  stop  to  set 
cross  hairs  horizontal  and  perpendicular.  The  centre  is  of 
hard  steel,  extra  long,  to  increase  steadiness.  The  leveling 
screws  are  made  large,  with  broad  edge  and  concave,  to  avoid 
unnecessary  weight,  and  are  capped  and  packed  to  prevent 
injury  from  dust.  This  instrument  is  made  with  three  or  four 
leveling  screws,  as  may  be  ordered,  and  does  not  detach  from 
the  leveling  plate.  It  is  packed  erect  in  hardwood  box,  with 
sunshade,  wrench,  screw  driver  and  adjusting  pins.  The 
tripod  is  our  improved  hardwood  split  leg  form.  Weight  of 
instrument,  22  Ibs.  ;  weight  of  tripod,  8  Ibs.  Price,  $250  oo 

A  1527.     Queen  Precision  Tunnel  Level,  same  as  A  1526,  furnished 
with  but  one  astronomical  eye-piece  of  40  diameters.     Ground 
glass  level,   mounted  under  telescope  instead  of  the  striding 
level  and  reflecting  mirror,  made  also  without  graduated  micro- 
meter screw.  Price,  $150  oo 


QUEEN   &   CO.,   INC.,    PHILADELPHIA. 


QUEEN"   ENGINEERS'   LEVEL. 


QUEEN   &   CO..    INC.,    PHILADELPHIA. 


59 


"QUEEN"   ENGINEERS'   LEVEL. 

The  illustration  on  previous  page  represents  our  Engineers'  Y  Level 
of  the  most  improved  construction,  with  telescope  of  the  finest  optical 
qualities,  and  is  made  in  three  lengths,  either  18,  20  or  22  inches  long,  and 
is  mounted  in  proportional  Y  supports  and  different  lengths  of  bars.  The 
telescope  has  object  glass  i  }£  inches  diameter  with  magnifying  power  about 
35  to  45  diameters,  as  may  be  ordered.  It  has  improved  and  patented 
screw  adjustment  to  eye-piece  of  telescope  for  focussing  cross  wires.  The 
draw  tube  is  provided  with  dust  cap  to  prevent  dirt  or  grit  from  entering 
the  body  tube. 

An  8-inch  level  is  securely  mounted  on  the  under  side  of  the  tele- 
scope and  is  uniformly  ground  and  has  scale  graduated  in  tenths  of  inches. 
The  run  of  bubble  over  one  division  of  the  scale  is  equal  to  15  seconds 
elevation. 

The  telescope  revolves  truly  in  the  Y's  and  has  bell  metal  collars  at 
each  end  which  are  turned  between  dead  centres  of  exactly  the  same  diam- 
eter. These  collars  rest  in  the  Y's  and  are  held  in  position  by  clips  which 
are  hinged  on  the  Y's  and  lock  with  taper-pins.  One  Y  clip  is  furnished 
with  a  horizontal  stud  insuring  the  accurate  position  of  the  horizontal  wire. 
The  Y's  are  large  and  strong,  made  of  the  best  bell  metal,  each  Y  having 
two  nuts,  one  of  which  is  adjustable  with  the  ordinary  steel  pin.  The  level 
bar  is  made  square  of  fine  bronze,  and  so  proportioned  us  to  have  the 
greatest  strength  in  the  parts  most  subject  to  severe  strain.  The  centre  is 
made  of  bell  metal  and  is  extra  long,  to  increase  steadiness.  The  leveling 
screws  are  made  large  with  broad  edge  and  concave,  to  avoid  unnecessary 
weight,  and  are  capped  and  packed  to  prevent  injury  from  dust.  The  level 
is  fastened  on  tripod  either  by  bevel  clamps  or  by  screw,  as  may.be  desired. 

The  instrument  is  packed  erect  in  box,  which  contains  sunshade, 
wrench,  a  screw  driver  and  adjusting  pins. 

A  1528.     Engineers'    Y    Level,    i8-inch    telescope    complete,   with 

tripod,  as  above.  Price,  $110  oo 

A  1529.     Engineers'   Y    Level,    2O-inch    telescope    complete,   with 

tripod,  as  above.  Price,  $110  oo 

A  1530.     Engineers'    Y    Level,    22-inch    telescope    complete,    with 

tripod.  Price,  $115  oo 

A  1531.  Light  Engineers'  Y  Level,  1 5-inch  telescope,  has  the  same 
general  arrangement  as  the  regular  engineers'  level,  but  the 
leveling  head  remains  attached  to  the  spindle,  and  the  whole 
instrument  is  somewhat  smaller  and  lighter ;  complete,  with 
tripod.  Price,  $10000 


QUEEN   &   CO.,    INC..    PHILADELPHIA. 


QUEEN"  ARCHITECTS'  LEVEL. 


A  1532. 

A  1532.  Architects'  Level,  as  illustrated  above,  is  an  admirable  in- 
strument and  can  be  highly  recommended,  as  it  has  met  with  a 
very  large  sale  among  architects,  builders,  millwrights  and 
others  engaged  in  construction,  and  among  engineers  and  sur- 
veyors, by  whom  it  is  used  in  city  work.  The  telescope  is  12 
inches  long,  of  the  finest  optical  qualities,  and  has  magnifying 
power  of  about  25  diameters.  It  has  truly  ground  level  ^of 
medium  sensitiveness,  which  is  graduated  and  securely  mounted 
under  the  telescope.  The  telescope  has  red  metal  collars,  which 
rest  in  the  Y's  and  are  held  in  position  by  clips  which  are 
hinged  and  locked  the  same  as  in  the  engineers'  level.  The 
instrument  turns  upon  a  horizontal  circle  3  inches  in  diameter, 
graduated  from  o  to  90  each  way,  and  is  read  to  5  minutes  by 
a  vernier  which  is  fixed  to  the  spindle.  The  instrument  is 
screwed  on  tripod  and  is  packed  in  box  fitted  with  sunshade, 
plumb  bob,  screw  driver,  adjusting  pins  and  metal  trivet. 

Price,  $50  oo 

A  1532;^.     Architect*'  Level,  same  a=>  A  1532  with  tangent  screw. 

Price,  $55  oo 


QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


61 


QUEEN  "  TILTING  LEVEL. 


A  1532^.  Architects'  Tilting  Level  is  the  same  as  the  Architects' 
Level  A  1532,  excepting  that  it  has  the  addition  of  an  attach- 
ment by  which  sights  of  45  degrees  above  or  below  the  hori- 
zontal can  be  taken.  This  attachment  is  a  small  set  of  standards 
screwed  into  the  centre  of  the  level  bar,  and  when  not  in  use 
can  readily  be  removed.  It  has  V-shap.ed  grooves  at  the  top 
to  receive  the  telescope  axle,  also  clamps  to  hold  it  in  place. 
The  small  axle  mounted  on  the  telescope  does  not  interfere 
when  the  instrument  is  used  as  an  ordinary  level.  Price,  $65  oo 

A  1532)^.     Architects'  Tilting  Level  with  tangent  screw.       Price,  $70  oo 


62 


QUEEN   &  CO.,   INC.,   PHILADELPHIA. 


QUEEN"  ARCHITECTS'  COMPASS   LEVEL. 


A  1533- 


A  1533.  Architects*  Compass  Level.  This  instrument  is  similar  to 
the  architects'  level  before  described,  but  is  fitted  with  com- 
pass with  2^ -inch  needle.  This  is  so  arranged  that  it  adds 
practically  nothing  to  the  weight  or  bulk,  and  does  not  inter* 
fere  with  the  portability  of  the  instrument,  whilst  its  value  in 
many  kinds  of  work  is  obvious.  The  instrument  is  screwed  on 
a  tripod  and  packed  in  a  box  fitted  with  sunshade,  plumb  bob, 
screw  drivers,  adjusting  pin  and  metal  trivet.  Price,  $65  oo 

~A  I533>^.  Architects'  Compass  Level,  same  as  A  1533  but  with 

tangent  screw.  Price,  $70  oo 


QUEEN   &   CO.,   INC.,   PHILADELPHIA.  65 

"QUEEN"   LAND  LEVEL. 

The  Queen  Land 
Level,  as  recently  intro- 
duced by  us,  is  the  only 
low-priced  instrument  on 
the  market  that  combines 
all  the  working  features 
of  the  finer  engineering 
transits  and  levels.  This 
complete  little  instru- 
ment, as  shown  in  the 
above  illustration,  is 
practically  indispensable 
to  engineers,  county  sur- 
veyors; farmers,  land- 
scape gardeners  and 
planters.  It  is  a  great 
labor  saver  to  the  wheel- 

A  1535.  wright  in  lining  and  set- 

ting up  shafting ;  to  the  builder  and  bricklayer  a  valuable  substitute  for 
the  primitive  level  board  formerly  used  in  setting  up  foundations,  floors, 
sills  and  running  grades.  It  is  also  an  excellent  instrument  for  the  scholar, 
illustrating  the  elementary  principles  of  engineering  and  surveying.  It  can 
be  used  for  angulation,  level  lines,  grading  streets,  sewers  and  drains. 

The  construction  is  extremely  simple,  having  as  few  parts  as  possible, 
and  combines  compactness  and  efficiency  so  that  anybody  can  at  once  wrork 
it  successfully  and  without  special  explanations.  The  telescope  is  8^  inches 
long,  having  achromatic  objectives,  with  magnifying  power  10  times.  The 
eye-piece  has  four  (4)  lenses,  showing  objects  in  their  natural  position.  The 
cross  wires  are  fixed  in  the  telescope  so  that  there  is  no  danger  of  their  losing 
the  adjustment.  The  level  is  mounted  on  top  of  the  telescope  and  is  pro- 
vided with  adjusting  screws.  The  telescope  and  level  are  securely  mounted 
on  a  swivel  bearing  which  permits  of  an  elevation  or  inclination  of  the  tele- 
scope 25  degrees  from  the  level  line,  and  can  be  clamped  in  any  position. 
The  leveling  frame  is  provided  with  four  (4)  leveling  screws  whose  lower 
ends  are  ball  jointed.  The  centre  is  cast  of  one  piece  with  the  leveling 
plate,  and  its  outer  edge  bevelled  and  graduated  into  degrees.  The  socket 
is  carefully  fitted  to  the  centre  of  the  leveling  frame,  and  is  also  provided 
with  a  clamp  screw.  The  arc  is  cast  on  this  socket  and  graduated  into 
degrees.  The  lower  end  of  the  leveling  plate  has  a  half  ball  which  connects 
the  tripod  plate  to  the  upper  part,  like  in  the  case  of  the  regular  transits  and 
levels.  The  instrument  is  screwed  to  a  substantial  tripod  and  is  packed  in  a 
wooden  carrying  case,  making  it  exceedingly  portable. 

A  1534.   Queen  Land  Level,  for  h or izontar angles.  Price,  $20  oo 

A  1535.    Queen  Land  Level,  for  horizontal  and  vertical  angles.  Price,  $25  oo 


64 


QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


ATTACHMENTS  AND  PARTS. 

A  1536.     The  Solar  Attachment,  as  shown  in  the  following  cut,  consists  of  a 
small   telescope    mounted    on  a  horizontal    axis,   which  rests  upon   two 

standards  connected  to  a  circular  base.  . 
This  base  is  the  socket  of  the  so-called 
polar  axis,  and  is  attachable  at  its 
lower  extremity  to  the  horizontal  axis 
of  the  telescope.  The  solar  telescope 
is  thus  capable  of  being  turned  on  its 
own  horizontal  axis  and  on  its  polar 
axis.  A  small  level  is  applied  parallel 
to  the  solar  telescope.  Two  pointers 
are  also  attached  for  use  as  a  specie  of 
finder,  the  sun  appearing  the  field 
of  view  of  the  telescope  when  the 
shadow  of  one  of  these  pointers  is 
thrown  on  the  other.  The  solar  tele- 
scope  is  provided  with  a  right  angle 
prism  for  conveniently  observing  the  sun  when  it  is  at  a  considerable  altitude. 
It  is,  of  course,  provided  with  shade  glasses  for  the  purpose  of  reducing  the 
intensity  of  the  solar  rays  transmitted.  The  small  graduated  circle 
sometimes  attached  to  the  polar  axis  enables  the  hour  angle  to  be  read  off. 
Clamp  and  tangent  are  provided  both  for  the  vertical  and  for  the  hour  angle  • 
movement.  For  instructions  as  to  how  the  solar  is  used,  we  refer  you  to 
our  Engineers'  Manual.  Price,  $60  oo 

A  1537.  Qradienter.  —  This  attachment  consists  mainly  of  a  screw  attached  to  the 
semi-circular  expanded  arm 
of  the  ordinary  clamp  of  the 
telescope  axis  ;  the  screw  is 
accurately  cut  to  a  given 
number  of  threads,  and  pas- 
sing through  a  nut  in  one  side 
of  the  arm  presses  against  a 
little  stud,  A,  fixed  to  the  in- 
side surface  of  the  right-hand 
standard.  As  the  value  of  the 
screw  thread  is  such  that  a 
complete  revolution  will 
move  the  horizontal  cross- 
wire  of  the  telescope  over  a 
space  of  one  foot  on  a  rod  at  a 
distance  of  one  hundred  feet, 
it  is  cl  ear  that  when  the  screw 
is  turned  through  fifty  spaces 
on  the  graduated  head,  the 
wire  will  pass  over  fifty  one- 
hundred  ths,  or  one-half  a  fc 


T537- 


In  this  way  the  gradienter 
Grades  can  also  be  estab- 


on  the  rod,  and  so  on  in  the  same  proportion. 

can  be  used  in  the  measurement  pf  distances. 

lished  with  great  facility,  as  follows  :  ist,  level  the  instrument;  bring  the 

telescope  level  to  its  centre  by  the  clamp  of  the  gradienter  screw  ;  move 

the  graduated  head  until  its  zero  is  brought  to  the  edge  of  the  scale,  and 

then  turn  off  as  many  spaces  on  tha  head  as  there  are  hundredths  of  feet  to 

the  hundrel  in  ths^ri'le  t  >  be  established.  Price,  $18  oo 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


A  1538- 

A  1538.  Queen's  Opposite  Vernier  Attachment  is  of  great  value  in 
cases  where  it  may  be  desirable  to  eliminate  errors  and  eccen- 
tricities in  the  graduation  and  veroiiers  of  the  vertical  circle  in 
the  same  manner  as  in  the  horizontal  graduation  by  reading 
two  opposite,  verniers.  As  the  vertical  circle  is  permanently 
attached  to  the  telescope  axle  and  cannot  be  turned  independ- 
ently, as  in  repeating  circles,  the  telescope  must  be  reversed 
when  a  repetition  of  the  angle  is  desired.  The  mean  of  the 
two  readings  is  then  accepted  as  the  true  result.  In  the  above 
illustration  the  vertical  circle  is  enclosed  in  an  outside  shield, 
fastened  to  which  are  two  opposite  double  verniers  reading  to 
single  minutes.  Two  opposing  capstan  head  screws,  working 
against  a  projecting  stud  on  the  standard,  are  provided  to  ad- 
just the  zero  point  on  the  verniers  to  coincide  with  those  of 
the  vertical  circle  after  the  instrument  has  been  leveled  up  and 
the  telescope  placed  in  a  truly  horizontal  position.  This  at- 
tachment can  be  put  on  a  5 -inch  full  vertical  circle  in  new 
instruments  only.  Price,  extra,  $20  oo 

The  above  illustration  of  the  Opposite  Vernier  Attachment 
shows  the  Vertical  Circle  covered  with  an  illuminum  dust 
cover  or  guard,  this  can  be  put  on  the  vertical  circle  of  any 
new  Queen  transit.  Price,  extra,  $5  oo 


66 


QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


A  1539. 


A  1539-  The  Telescope 
Attachment  for  Survey- 
ors' Compass  is  attached 
in  the  same  manner  and  takes  the 
place  of  the  regular  standard,  and  can 
be  furnished  as  an  extra  for  new  in- 
struments or  independently  be  used  on 
any  surveyors'  compass  made.  The 
telescope  is  9  inches  long,  fine  optical 
quality,  with  magnifying  power  of  20 
diameters.  Has  regular  -focussing  and 
slide  tube  for  eye-piece ;  ground  level 
tube  on  top  of  telescope;  3^ -inch  vertical 
circle,  graduated  in  ^  degrees  and  reading 
by  vernier  to  3  minutes.  The  telescope 
revolves  for  back  sighting,  and  has  clamp 
and  tangent  attachment.  Complete,  in- 
cluding counterpoise.  Price,  $30  <x* 


A  1540.  A  1541. 

Detachable  Telescopes  for  Vertical  Sighting. — The  two  forms  of  de- 
tachable telescope  shown  in  the  above  illustrations  can  be  attache^  to  any  of 
the  Queen  transits.  The  side  telescope  shown  in  A  1541  is  fitted  by  a  flange 
and  disk  connecting  it  with  the  axis,  so  as  to  make  it  exactly  parallel  with 
the  main  telescope.  Counterpoise,  as  shown,  is  fitted  to  the  other  end,  and 
both  can  be  detached  at  pleasure.  The  top  telescope,  as  shown  in  A  1540, 
is  connected  with  the  main  telescope  by  coupling  nuts,  which  fasten  it 
securely  directly  over  the  centre  of  the  instrument  and  allow  its  ready 
removal  and  replacement  without  disturbing  its  adjustment. 

In  both  of  the  above  forms  the  extra  telescope  is  adjusted  to  the  main 
telescope  of  the  transit  so  that  the  lines  of  collimation  of  both  are  parallel 
and  in  the  same  plane — horizontal  in  A  1541  and  vertical  in  A  1540. 
Price  of  either  telescope,  A  1540  or  A  1541,  $25  oo 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


A  1542. 


A  1542.  Cross  Wire  Reflector.  An  elliptical  sil- 
vered plate  inclined  at  an  angle  of  45  degrees 
with  its  ring,  which  is  fitted  to  the  object  end 
of  the  telescope.  The  hole  in  the  centre  of 
the  reflector  allows  the  use  of  the  telescope, 
while  a  light  held  near  the  inner  surface  illumi- 
nates the  cross  wires.  Price,  $4  oo 


A  1543- 


A  1543.  Diagonal  Prism.  This  is  used  where 
greater  vertical  angles  are  to  be  taken  than  are 
possible  with  the  ordinary  telescope.  Obser- 
vations can  be  taken  with  a  prism  up  to  an 
angle  of  60  degrees  elevation.  Price,  $8  oo 


A  1544.  Queen's  Compass  Telescope  as  shown  in 
the  illustration  is  made  to  attach  to  the  com- 
pass standard  and  is  of  great  value  where  long 
sights  are  to  be  taken.  The  telescope  is  9 
inches  long,  with  magnifying  power  of  20 
diameters.  Price,  $18  oo 


A  1545.  Plummet  Lamp.  A  large  plum- 
met, of  which  the  upper  part  ''s  hollow 
to  contain  oil.  It  also  has  a  tube  for 
a  wick,  covered  by  a  screw  cap.  It  is 
hung  in  gimbals  by  a  chain  with  hook 
and  so  always  assumes  a  vertical  posi- 
tion. These  plummets  are  generally 
packed  in  pairs  in  hardwood  case  fur- 
nished with  straps  to  sling  over  the 
A  1544.  shoulders.  Price,  $10  oo 


68  QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


EXTRAS   FOR  TRANSITS,   LEVELS,  COMPASSES 

ALSO   PARTS  OF   INSTRUMENTS   LIABLE 

TO   LOSS  OR   INJURY. 

TRANSITS. 

Solar  Attachment $60  oo 

Diagonal  Prism  for  Eye-Piece    . .  8  oo 

Reflector  for  Object  Glass  of  Telescope ,,  ...   .   .  4  oo 

Sunshade . i  oo 

Stadia  Wires 4  oo 

Cross  Hairs  and  Diaphragm 4  oo 

Cap  for  Objective *','•/.*, 75 

Bye-Piece,  complete     . , 6  oo 

Objective,  complete 6  oo 

Sights  on  Telescope  with  Folding  Joint  . ,....,  8  oc 

Sights  on  Standards  at  Right  Angles  to  Telescope    .    .         .....  5  oo 

Rack  and  Pinion  Movement  to  Eye-Piece    .    .    .  .  <  .  V  • 5  oo 

Needle  and  Centre  Pin 2  50 

Level  on  Telescope  with  Ground  Bubble  and  Scale 1 2  oo 

Ground  Glass  Level  Vial  for  Plate  or  Standards .each,  i  oo 

Ground  Glass  Level,  brass  mounted,  complete,  for  Plates  or  Stand- 
ards    -„.••  . each,  2  50 

Clamp  and  Tangent  to  Axis  of  Telescope 5  oo 

Vertical  Circle,  3^  inches  in  diameter,  divided  on  silver,  vernier 

reading  to  5  minutes 8  oo 

Vertical  Circle,  4^  inches,  divided  on  silver,  vernier  reading  to  single 

minutes '•'..' 1 2  oo 

Vertical  Arc,  6  inches,  divided  on  silver,  with  vernier  moved  by 

tangent  screws  reading  to  30  seconds .  18  oo 

Clamp  Screw  for  Horizontal  Limb •    •   •  75 

Clamp  Screw  for  Leveling  Head , ,*  75 

Tangent  Screw  for  Horizontal  Limb , i  50 

Tangent  Screw  for  Leveling  Head ,    .    .  150 

Leveling  Screws  for  Leveling  Head i  50 

Graduations  on  Limb,  on  solid  silver  ......    . '  .    .    .    .    ,    .    .  15  oo 

Graduations  on  Limb,  on  solid  silver,  to  20  or  30  seconds 20  oo 

Graduations  of  Limb,  on  solid  silver,  to  10  seconds .  30  oo 

Mahogany  Boxes,  with  lock  and  key,  strap,  and  fitted  inside  .  $4.06  to  8  oo 

Leather  Case,  with  shoulder  straps,  lock  and  key,  fitted  inside,  $8.00  to  12  oo 


QUEEN   &  CO.,    INC.,   PHILADELPHIA.  69 

"Y"  LEVELS. 

Ground  Glass  and  Graduated  Level  Vials  in  Telescppe $5  oo 

Cap  for  Object  Glass 75 

Rack  and  Pinion  Movement  to  Eye-Piece 5  oo 

Clamp  Screw  for  Leveling  Head    .    .    ...    .   ...   .*.   .    .   .    .   .100 

Tangent  Screw  for  Leveling  Head i  50 

Leveling  Screw  for  Leveling  Head , i  50 

Eye-Piece,  complete 6  oo 

Objective,  complete     .   .    ..  .  ~.  V  .   .    .    .    .-.-.- 7  oo 

Cross  Wires  and  Diaphragm 4  oo 

Mahogany  Boxes,  with  lock  and  key,  strap,  and  fitted  inside  .  $4.50  to  6  oo 

COMPASSES. 

Needle  and  Centre  Pin .    .  1 '  ...  $2  50 

Centre  Pin , 50 

Plain  Glass  Level  Vials     . each,  25 

Plain  Glass  Level  Vials,  brass  mounted,  complete 3  i  50 

Glass  Cover 'for  Compass  of  our  own  make i  oo 

•Out-Keeper i  oo 

Glass  Circle  to  Compass  Face 50 

Staff  Mountings,  complete,  for  Pocket  Compasses,  small  size     ...  2  50. 

Stafi  Mountings,  complete,  for  Surveyors'  Compasses     :            ...  5  oo 

Compass  Sight  Rings ; 2  50 

Clamp  Screw  for  Leveling  Head 75 

Tangent  Screw  for  Leveling  Head    -        i  50 

MISCELLANEOUS. 

Re- Graduating  Horizontal  Limb  and  Verniers  of  Transits $1000 

Re-Graduating  Vertical  Limb  and  Verniers  of  Transits    ......  5  oo 

Tripod  Heads  only,  with  bolts  and  nuts,  to  fit  any  Transit  of  our 

make 5  oo 

Wood  Cap,  with  brass  screw,  to  fit  any  Tripod  of  our  make  ....  75 

Solid  Metal  Points  or  Shoes  for  Tripod  Legs  .    .*   .   , 50 

Leather  Carrying  Strap  for  Tripods  ,.;.;. 50 

Reading  Magnifiers  for  Transits 75 

Chamois  Skins  for  cleaning  instruments,  best  quality .  65 

Waterproof  Rubber  Cover  for  Transits  and  Levels each,  i  oo 

Fine  Oil  for  surveying  instruments   ..........  per  bottle,  25 

Steel  Adjusting  Pins each,  10 

Screw  Drivers " each,  20 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


SPIRIT  LEVELS. 


Level  Vials  for  telescope  for  1 2 -inch  level $400 


Do. 
Do. 
Do. 
Do. 
Do. 
Do. 


do. 
do. 
do. 
do. 
do. 


15 
18 
20 

22 


do. 
do. 
do. 
do. 


transits  . 


for  plates  of  transits 


5  oo 

6  oo 

7  oo 
7  oo 
4  oo 
i  50 


Level  Vials  for  Machinists'  Levels,  8  inches $4  oo 

Do.  do.  10     do.       v 5  oo 

Do.  do.  12     do 6  oo 

Do,  do.  15     do. 7  oo 


Level  Vials,  ground  and  graduated,  made  to  order  from  any  specifications. 


inches $o  60 

"      V..-     75 

11    ..,.  /.  .VY     85 

I    00 

"    I  25 

"       i  50 

**       i  75 

"  2    00 


9 
10 


inches $2  50 


3  50 

4  oo 

4  50 

5  oo 

6  oo 

7  oo 


Level  ViaJs,  plain  and  not  graduated. 
i  inch  to  4  inches    .   .    .   .  $o  25 


inches  to  6  inches  .    .    .  $o  50 


QUEEN   &  CO.,    INC.,   PHILADELPHIA.  71 


REPAIR  WORK. 

Costs  for  repairs  are  charged  by  the  time  occupied  (so  much  per 
hour)  on  the  instrument,  and  as  the  instrument  generally  passes  through 
three  hands,  these  are  classed  under  three  heads  : 

First,  the  time  occupied  in  taking  apart  the  entire  instrument, 'exam- 
ining each  separate  part  in  a  lathe  to  see  whether  it  is  bent  or  worn ,  and 
rectifying  if  necessary. 

Secondly,  follows  what  is  termed  the  "  Instrument  Makers'  Adjust- 
ment " — the  properly  placing  and  screwing  of  all  these  parts  together  again, 
seeing  that  they  work  smoothly  and  correctly,  and  (if  it  be  a  transit)  that 
the  centres  have  no  shake,  that  the  vernier  and  graduations  are  properly 
adjusted  and  centred,  that  the  telescope  slides  are  without  shake  and  move 
properly,  that  the  centre  pin  is  sharpened,  needle  magnetized,  and  the  levels 
still  tightly  cemented  in  their  tubes  ;  in  fact,  seeing  that  everything  is  cor- 
rect, and,  if  necessary,  giving  any  defective  parts  back  into  the  workman's 
hands  for  correction  ;  and  as  this  consumes  as  much  time  for  a  slightly 
injured  as  for  the  most  seriously  injured  instrument,  the  charges  for  this 
item  are  in  some  cases  as  much  as  for  the  original  repairs. 

Thirdly,  follows  the  "  Engineers'  Adjustment"  proper,  seeing  that 
the  magnetic  needle  and  centre  pin  are  in  adjustment,  adjusting  the  levels 
so  that  they  will  reverse,  adjusting  the  cross  wires  of  the  telescope  so  that 
they  will  traverse  a  vertical  line,  and  be  in  "  line  of  collimation,"  and  (if  it 
be  a  "  Complete  Transit  and  Leveling  Instrument")  seeing  that  the  long 
level  under  the  telescope  is  in  true  level  and  adjustment. 

If  any  express  charges  have  been  paid  by  us,  these  are  placed  under 
a  separate  item  ;  any  cabinet  work  that  may  have  been  done  to  the  box  is 
also  itemized  ;  packing  expenses  are  charged  at  cost. 

In.  order  to  do  justice  to  the  engineer  and  ourselves,  it  is  always 
advisable  to  have  an  examination  made  and  a  quotation  submitted  before 
starting  the  work,  thus  avoiding  any  misunderstandings. 

We  employ  skilled  labor  that  thoroughly  understand  the  repairing  of 
all  makes  of  instruments  ;  we  therefore  invite  the  wcrk  required  en  any 
instrument  made. 


QUEEN   &   CO.,    INC.,   PHILADELPHIA. 


LEVELING  RODS. 


A  1547- 


A  1546.    A  1548.    A  1550.    A  1553.    A  1554. 


QUEEN  &  CO.,  INC.,  PHILADELPHIA.  73 


LEVELING  RODS. 


A  1546.  Philadelphia  Rod,  divided  into  feet,  tenths  and  hundredth 
of  a  foot,  verniers  reading  to  thousandths,  with  target,  vernier 
and  clamp,  71  <y  feet  closed,  sliding  to  13  feet.  $16  oo 

A  1547.  Philadelphia  Rod,  divided  into  feet  and  tenths,  vernier 
reading  to  hundredths,  with  target,  vernier  and  clamp,  7i3o  feet 
closed,  sliding  to  13  feet.  14  oo 

A  1548.  Philadelphia  Mining  Rod,  divided  into  feet  and  tenths,  ver- 
nier reading  to  hundredths,  with  target,  vernier  and  clamp, 
4  feet  closed,  sliding  to  7  feet.  12  oo 

A  1549.  Philadelphia  Metric  Rod,  divided  into  meters,  decimeters 
and  centimetres,  vernier  reading  to  millimeters;  target,  ver- 
nier and  clamp.  16  oo 

A  1550.  New  York  Rod,  divided  into  feet,  tenths  and.  hundredths, 
vernier  reading  to  thousandths,  with  target,  vernier  and 
ciamp,  6  is  feet  closed,  sliding  to  12  feet.  14  oo 

A  1551     New  York  Rod,  same  as  A  1550,  in  three  parts,  5  feet  closed, 

sliding  to  13  feet.  18  oo 

A  1552.     New  York  Rod,  same  as  A  1550,  in  4  parts,  5  feet  closed, 

sliding  to  16  feet.  20  oo 

A  1553-     Boston  Rod,  divided  into  feet,  tenths  and  hundredths,  6^ 

feet  closed,  sliding  to  n  feet.  14  oo 

A  1554.  Architects'  Rod,  divided  into  feet,  tenths  and  hundredths, 
vernier  reading  to  thousandths  ;  target,  vernier  and  clamp  ; 
5^  feet  closed,  sliding  to  10  feet.  6  oo 

A  1555.     Architects'  Rod,  divided  into  feet,  inches  and  sixteenths ;" 

target  and  clamp  ;  5^  feet  closed,  sliding  to  10  feet.  6 


QUEEN    &   CO.,    INC.,    PHILADELPHIA. 


ii 


A.  1556. 


A  1558,    A  1559.   A  1561 


A.  1560 


QUEEN   &  CO.,    INr.,   PHILADELPHIA.  75 


A  1556.     Telescopic    Self-reading    Rod,    brass   mountings,    5   feet 

closed,  sliding  to  14  feet.  $24  oo 

• 

A  1558.     Cross  Section   Rod,   10  feet,  divided  into  feet,  tenths  and 

hundreths  on  both  sides,  tevel  bubble  at  each  end.  10  oo 

A  1559.     Stadia  Rod,  self-reading,  folding  with  strong  brass  hinge, 

6  feet  closed,  opening  to  12  feet.  12  oo 

A  1560.     Leveling  Pole,  octagonal,  tapered,  steel  shoe,  divided  in  feet, 
painted  red  and  white  alternately. 

6  ft.     •  8  ft.  10  ft. 


$2.00  $2.25  $2.50 

A  1561.     Leveling  Pole,  flat,  tapered,  steel  shoe,  divided  in  feet, 
painted  red  and  white  alternately. 

6  ft.  8  ft.  10  ft. 


$2.00  $2.25  $2.50 

A  1562.     Iron  Tubular  Pole,  J/%  inch  in  diameter,  painted  red  and 
white  alternately. 

6  ft.  8  ft.  10  ft. 


$2.75  $3.00  $3.50 

A  1563.     Iron  Pole,  "/%  inch  in  diameter,  hung  in  gimbals,  painted 

red  and  white  alternately,  6  feet  long.  4  oo 

*»  1564.     Leveling  Pole,  octagonal,  tapered,  steel  shoe,  painted  red 
and  white  alternately  every  half  meter. 

2  meters.  2^  meters.  3  meters. 

$2.50  $3.00  $3.75 


76 


QUEEN   &  CO.,   INC.,   PHILADELPHIA. 


TRIPODS. 


A  1569.  A  1572.  A  1565. 

A  1565.     Hardwood  Solid  Leg  Tripod,  large  size $10  oo 

This  Tripod  is  used  with  City,  Engineers'  and  Surveyors'  Transits  and 
Engineers'  Y  Levels. 

A  1566.     Hardwood  Solid  Leg  Tripod,  medium  size    .    .   .    .    .   .    .      8  oo 

This  Tripod  is  used  with  Mining,  Reconnoissance,  Builders'  Transits 
and  Architects*  Levels  and  Surveyors'  Compasses. 

A  1567.     Hardwood  Solid  Leg  Tripod,  small  size  ...    ......      600 

A  1568.     Hardwood  Solid  Leg  Tripod,  Jacob  staff  head 300 

This  Tripod  is  used  for  Hand  Levels  and  Surveyors'  Compasses. 
A  1569.     Hardwood  Split  Leg  Tripod,  large  size  .    ........     12  oo 

Used  on  same  instruments  as  A  1565. 
A  1570.     Hardwood  Split  Leg  Tripod,  medium  size .     10  oo 

Used  on  same  instruments  as  A  1566. 
A  1571.     Hardwood  Split  Leg  Tripod,  small  size 8  oo 

Used  on  same  instruments  as  A  1567. 
A  1572.     Patent  Extension  Leg  Tripod,  large  size l   .     15  oo 

Used  on  same  instruments  as  A  1565. 

A  1573.     Patent  Extension  Leg  Tripod,  medium  size 12  oc 

Used  on  same  instruments  as  A  1566. 

A  1574.     Patent  Extension  Leg  Tripod,  small  size 10  oo 

Used  on  same  instruments  as  A  1567. 

A  1575.     Hardwood  Solid  Legs  Only,  per  set »    ,    ...  5  oo 

A  1576.     Hardwood  Split  Legs  Only,  per  set 6  oo 

A  1578.     Extension  Legs  Only,  per  set 10  oo 

A  1579.     Jacob  Staffs 2  oo 


-v   \ 


a  r^\. 

X 

QUEEN   &   CO.,    INCV   ¥frlLA~DELPHIA. 

POCKET  COMPASSES. 


77 


A  1580.  A  1581. 

A  1580.     Pocket  Compass,  brass,  watch  pattern,  paper  dial. 

i#  i#  J^ 

$0.40  $0.50  $0.60  each. 

A  1581.     Pocket  Compass,  brass,  with  cover,  paper  dial. 

i& 
$0.55  each. 


A  1582. 

A  15^2.     Pocket  Compass,  brass,  watch  pattern,  metal  dial,  agats  centre, 
with  needle  stop. 

itf  i^  2 

$0.65  $0.80  $1.00  each. 


A  1583. 

1583.     Pocket  Compass,  mahogany  case,  metal  dial,  agate  centre,  with 
needle  stop. 

ll/2  2  2%  Z 

$1.50       $2.00       $2.25       $2. 50  each. 


QUEEN   &   CO.,    INC.,    PHILADELPHIA, 


A  1584. 


A  1585. 


A  1584.     Pocket  Compass,  brass,  watch  pattern,  metal  dial,  raised  ring, 
agate  centre,  with  needle  stop. 


$1-25 


$1.50 


$1.75  each. 


A  1585.     Pocket  Compass,  brass,  with  cover,  metal  dial,  agate  centre,  with 
needle  stop. 


$1-00 


$1.50 


$2.00  each. 


A  1586. 


A  1587. 


I 


A  1586.     Pocket  Compass,  nickel  plated,  watch  pattern,  raised  ring,  agate 
centre,  bar  needle,  improved  needle  stop. 

13/8 


1/2 


$2.75 


$3.00. 


$3.25  each. 


A  1587.     Pocket  Compass,  nickel  plated,  watch  pattern,  agate  centre,  bat 
needle,  improved  needle  stop. 


-50 


$3.75  each. 


QUEEN   &   CO.,   INC.,    PHILADELPHIA. 


A  1588.  A  1589. 

A  1588.     Pocket  Compass,  nickel  plated,  hunting  case,  watch  pattern,  agate 
centre,  bar  needle,  improved  needle  stop. 

i#  itf  2 

$3.75  $4.00  $4.50  each. 

A  1589.     Pocket  Compass,  nickei  plated,  with  cover,   raised  ring,  agate 
centre,  bar  needle,  improved  needle  stop. 

iX  1%  2 

$2.25  $2.50  $2.75  each. 


A  1590.  A  1592. 

A  1590.     Pocket  Compass,  nickel  plated,  hunting  case,  raised  ring,  agate 
centre,  bar  needle,  improved  needle  stop,  folding  sights. 

2  2^ 

$4.25  $7. oo  each. 

A  1591.     Pocket  Compass,  same  as  A  1590,  with  two  right  angle  levels, 

2^  inches,  $8.00. 
A  1592.     Pocket  Compass,  nickel  plated,  hunting  case,  stem  stop,  Singer's 

card  dial.  ij^  i^ 

$2.25  $2.50  each. 

A  1592 >£.    Pocket  Compass,  nickel  plated,  hunting  case,  stem  stop,  Singer's 
pearl  dial.  i^4  i^i 

$3.50  $4.00  each. 


8o 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 

SIGHT  COMPASSES. 


A  r593-  A  1594. 

A  1593-     Pocket   Compass,  bronzed,  ring  divided  in  single  degrees,  agate 
centre,  bar  needle,  folding  sights,  mahogany  case. 

2  2}^  3 

$5-50  $6.00  $6. 50  each. 

A  1594.    Pocket  Compass,  nickel  plated,  with  cover,  agate  centre,  bar  needle, 
folding  sights.        i^  2  2^3 

$4-50  $5-50  $6.50 

A  1595-     Pocket  Compass,  brass,  with  cover,  agate  centre,  bar  needle,  fold- 
ing sights.  I>2  2  2>£ 
..oo                J.s.oo                $6.00 


A  1596. 


A  1596-     Pocket  Surveying  Compass,  brass,  octagonal,  agate  centre,  bar 
needle,  folding  sights,  Jacob  staff  mounting,  mahogany  case. 

2^  3 


$7-00 


>.oo 


1.00 


QUEEN    &   CO.,    INC.,   PHILADELPHIA. 


Si 


GEOLOGISTS1  AND  MINERS'  COMPASSES. 

GEOLOGISTS'    COMPASSES. 

These  compasses  are  applied  to  ascertain 
the   angles   of  ' '  dip  ' '    and    ' '  strike  ' '    in    the 
strata  of  rock  formations.     Each  instrument 
is   furnished   with   a   clinometer   attachment, 
which   consists   of  a   pendulum    with    index 
traversing  divisions  upon  the  inner  compass 
face,  and  an  armature  sliding  from  within  the 
casing  for  establishing  the  base  to  clinometer. 
Geologists'  Compass,  open  glass  face,  metal 
casing,  silvered  dial  with  clinometer  de 
grees,   and  raised  compass  ring   divided 
from  o  to  360  degrees,  agate  centre  an& 
stop  to  needle.  2^         2^       3  in. 

A  1597.     Nickel-plated,    $5.00     $6.00     $7.00 
A 1597.  A  1598.     Brass,  4.50       5.50       6.50 

MINERS'    COMPASSES. 

In  the  hands  of  the  prospector  the 
miners'  compass  or  dipping  needle  proves 
a  serviceable  guide  to  the  discovery  and 
location  of  magnetic  iron  ore.  In  this 
instrument  the  magnetic  needle  is  care- 
fully balanced  upon  a  horizontal  axis 
within  a  graduated  circle,  and  in  which 
the  needle  will  be  found  to  assume  a 
position  inclined  to  the  horizon.  This 
angle  of  deviation  is  called  the  inclination 
or  dip,  and  varies  in  different  latitudes, 
and  even  at  different  times  in  the  same 
place.  Hence,  in  reading  the  dip  for  the 
suspected  presence  of  magnetic  iron  ore 
the  observer  must  not  only  be  governed  by  his  instrument,  but  must  also 
draw  into  requisition  his  knowledge  of  the  general  geological  formation  of  the 
place  of  his  survey ;  and  dependent  on  his  experience,  he  will  be  enabled  to 
approximate  as  to  the  probable  mass  and  depth  of  the  ore  from  the  surface. 
When  in  use,  the  instrument  should  be  held  suspended  by  the  ring,  and  the 
needle  permitted  to  swing  north  and  south,  by  placing  the  plane  of  the  circle 
in  that  of  the  magnetic  meridian.  The  inclination  of  the  needle,  as  read  off 
on  the  graduated  circle,  will  show  the  dip. 

A  1599.  Miners*  Compass  or  Dipping  Needle,  2^ -inch  magnetic 
needle  delicately  balanced  on  adjustable  agate  centres,  and 
traversing  graduated  3 -inch  silvered  arc  of  1 80  degrees,  with 
improved  stop  to  needle,  and  suspensory  ring,  highly  sensitive  ; 
in  case.  Price,  $12  oo 

This  instrument  is  warranted  to  be  the  best  of  its  kind 'in  the  market,  being 
unexcelled  in  point  of  delicacy,  finish  and  efficiency. 


A  1599- 


82  QUEEN   &   CO.,   INC.,   PHILADELPHIA. 

PRISMATIC  COMPASSES. 

The  advantage  of  the  prismatic  compass  is  that  the  distant  point  and 
the  graduation  of  the  compass  are  visible  at  the  same  time,  the  graduations 
being  upon  a  ring  attached  to  the  compass  needle  and  move  with  it ;  thus 
one  of  the  divisions  will  always  appear  directly  continuous  with  vertical 
hair  of  the  sight  vane.  The  prismatic  compass  is  used  in  preliminary  recon- 
noissances,  in  clearing  out  lines,  in  filling  in,  in  topographical  surveying,  etc. 


A  1600. 


A  1600.    Combined  Prismatic  Compass,  Clinometer  and  Altimeter, 

bronzed,  pocket  size,  2^  inches,  floating  card  compass  dial 
upon  agate  centre,  with  automatic  stop  and  spring  check ; 
mounted  beneath  2^ -inch  pendulum  dial  C,  graduated  for* 
altitude  o  to  1 80  degrees ;  also  divided  o  to  90  degrees  both 
ways  as  clinometer,  and  bearing  scale  of  rise  or  fall  in  inches 
per  yard.  Folding  prism  and  sight  vane  with  vertical  wire. 
Bronze  metal  case,  with  cover  and  also  leather  sling  case. 

Pric»4  $27  oo 

This  instrument  when  used  as  a  prismatic  compass  is  placed  in  a 
horizontal  position,  the  altitude  and  clinometer  dial  C  being  fixed  by  stop  D 
so  that  the  compass  divisions  are  rendered  visible  through  the  opening  at  C, 
thus  rendering  the  instrument  operative  in  the  usual  manner.  As  altitude 
instrument,  it  is  placed  in  a  vertical  position,  the  stop  D  being  released, 
thus  causing  the  divisions  of  the  altitude  arc  G  to  swing  in  view  of  and  in 
line  of  the  prism  and  hair  sight ;  when  applied  as  horizontal  clinometer,  the 
readings  are  observed  through  opening  E,  which  corresponds  to  the  position 
of  the  clinometer  base. 


QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


A  i6o[.  A  1603. 

A  1601.  Hutchinson's  Prismatic  Compass,  bronzed,  nearly  en- 
closed top,  floating  card  dial,  2  inches  in  diameter,  graduated 
to  ^  degrees,  agate  centre,  improved  stop  and  spring  check, 

sight  vane  with  vertical  wire  ;  morocco  case $i  i  oo 

A  1602.     Same  as  A  1601,  3  inches  in  diameter,  leather  sling  case  .     16  oo 
A  1603.     Prismatic  Compass,  floating  metal  dial,  3  inches  in  diam- 
eter, graduated  to   ^   degrees,  agate  centre,  improved  stop, 
folding  prism  and  sight  vane  ;  leather  sling  case 12  oo 


A  1604.  A  1605. 

A  1604.  Prismatic  Compass,  Barker's  patent,  bronzed  hunting  case , 
can  be  used  as  an  ordinary  compass  without  opening  the  cover, 
and  as  a  prismatic  compass  by  raising  the  cover  ;  glazed  at  S 
with  plate  glass,  on  which  is  etched  a  line,  answering  for  the 
sight;  with  Singer's  patent  card  dial,  2  inches 15  oo 

A  1605.     Prismatic  Compass,   3-inch  floating  silver  compass  ring* 
divided  into  ^  degrees,  folding  prism  and  hair  sight,  stop  to 
compass  effected   by  folding  the  hair  sight,   with  socket  for 
Jacob  staff;  leather  sling  case 14  oo 


QUEEN   &   CO.,    INC.,    PHILADELPHIA. 


PRISMATIC  COMPASSES. 


A  1606. 

A  1606.  Prismatic  Compass,  3  inches  in  diameter,  floating  alumin- 
ium dial,  automatic  stop  and  spring  check,  graduated  to  ^ 
degrees,  agate  centre,  folding  prism  with  shades  ;  sight  vane, 
with  vertical  wire  and  mirrors  ;  leather  sling  case  .  .  ...  .  $20  oo 

A  1606^.     Same  as  above,  Jacob  staff  mounting 22  50 

SIGHT  COMPASS  AND  CLINOMETER. 


A  1607. 

A  1607.  Bronzed  Sight  Compass  and  Clinometer,  2^  inches  in 
diameter,  engraved  metal  dial,  graduated  to  2  degrees,  bar 
needle,  with  stop;  agate  centre.  The  sights  are  connected  by 
a  bar  across  the  top,  which,  when  turned  down  serves  as  the 
fiduciary  edge  in  using  the  instrument  as  a  clinometer.  The 
clinometer  is  graduated  to  give  slopes  in  inches  per  yard  and 
in  degrees  ;  in  mahogany  box 7 

A  160$.     Same  as  above,  3  inches  in  diameter 8 


25 
75 


A i  609.     Same  as  above,  4  inches  in  diameter 10  50 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


POCKET  SURVEYORS'  COMPASS 


A  1 6  ro. 

A  1610.  Surveying  Compass,  with  folding  sights,  needle  3^  inches 
long,  nonius  on  side  of  compass,  box  for  adding  and  subtract- 
ing magnetic  variations,  two  straight  levels,  Jacob  staff 
mountings ,  ......  $i  6  oo 

A  1611.     Same  as  above  but  with  \y2  -inch  needle     ........     18  oc 

A*  1612.  Surveying  Compass,  same  as  A  1610,  but  without  nonius, 

needle  3^  inches  long 13  50 

A  1613.  Surveying  Compass,  same  as  A  1612,  without  levels  and 

nonius,  needle  3^  inches  long 1200 

A  1614.     Surveying  Compass,  same  as  A  1613,  but  needle  2^/2  inches 

long 10  o 

Tripod,  with  cherry  legs,  for  any  of  aboye  compasses   .   , 700 


86 


QUEEN  £  CO.,   INC.,   PHILADELPHIA. 


VERNIER  SURVEYORS'  COMPASS  WITH 
TELESCOPE. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA.  87 


VERNIER  SURVEYORS'  COMPASS  WITH 
TELESCOPE. 

The  Variation  Compass  with  Telescope  is  a  valuable  combination  for 
surverors,  as  it  is  not  only  a  surveyors'  compass,  but  combines  the  practical 
working  features  of  the  transit.  The  needle  is  four  inches  long,  and  the 
graduated  compass  ring  is  slightly  inclined  to  facilitate  the  reading  of  the 
needle.  A  variation  plate  is  attached  and  is  operated  by  loosening  the  clamp 
screw  so  that  the  compass  ring  can  be  moved  in  Azimuth  to  set  off  the  mag- 
netic variation  of  the  needles.  It  also  has  a  circle  for  reading  horizontal 
angles,  graduated  into  ^  degrees,  under  the  glass  cover  of  the  telescope 
box;  the  vernier  of  which  reads  to  one  minute,  and  is  fastened  to  the 
centre,  becoming  part  of  the  main  socket.  A  clamp  and  tangent  screw  with 
opposing  spring  is  attached  to  facilitate  the  reading  of  the  vernier.  Two 
ground  glass  levels  are  placed  at  right  angles  on  top  plate.  The  telescope 
is  9  inches  long,  of  fine  optical  quality,  with  magnifying  power  of  about  20 
diameters.  It  has  rack  focussing  and  sliding  tube  for  eye-piece.  A  truly 
ground  level  is  attached  on  top  of  telescope.  The  vertical  circle  is  gradu- 
ated in  Y^.  degrees  and  reads  by  vernier  to  three  minutes.  The  telescope 
revolves  for  back  sighting  and  has  clamp  and  tangent  attachment.  The 
telescope  supports  are  screwed  in  same  place  as  the  sights  and  are  balanced 
on  opposite  sides  by  a  counterpoise.  The  sights  are  also  furnished,  and  are 
graduated  into  ^  degrees  on  the  edge  for  angles  of  elevation  or  depression. 
The  lower  part  has  four  leveling  screws  and  clamp  and  tangent  movement. 
The  instrument  is  readily  attached  to  the  tripod  by  a  screw  fastened  on  head 
of  tripod.  The  telescope  and  sights  are  detachable  and  packed  in  case 
with  the  compass.  The  box  is  fitted  with  plumb  bob,  screw  drivers, 
wrench,  etc. 

A  1615.     Vernier  Compass,  with  telescope  and  tripod  and  leveling 

screws  complete,  as  above.  Price,  $75  oo 


88 


QUEEN   &    CO.,    INC.,   PHILADELPHIA. 


THE  PLAIN   COMPASS, 


A  1610. 


QUEEN    &   CO.,    INC.,    PHILADELPHIA.  89 


THE   PLAIN   COMPASS. 

The  Plain  Compass  as  now  made  with  all  our  extra  attachments  and 
furnished  at  a  very  slightly  increased  price,  can  be  highly  recommended,  as  it 
enables  the  surveyor  to  accomplish  twice  the  amount  of  work  that  can  be  done 
by  the  old  form.  The  needle  is  made  in  three  different  lengths,  four,  five  and 
six  inches,  and  the  plates  are  thirteen,  fourteen  and  fifteen  inches  long 
respectively.  The  compass  rim  is  sligtly  inclined  to  facilitate  the  reading  of 
the  needle,  and  is  graduated  into  ^  degrees,  figured  in  quadrants.  Two 
ground  glass  levels  are  placed  at  right  angles  on  top  plate.  The  sights  are 
graduated  into  *4  degrees  on  the  edges  for  angles  of  elevation  or  depression. 
The  lower  part  has  four  leveling  screws  and  centre  clamp  screw. 
The  instrument  is  readily  attached  to  the  tripod  by  a  screw  fastened  on  the 
head  of  tripod.  The  sights  are  detachable  and  are  packed  in  case  with  the 
instrument.  The  case  is  fitted  with  plumb  bob,  screw  driver,  wrench,  etc. 

A  1616.     Plain  Surveying  Compass,  4-inch  needle,  13-inch  plate,  as 

above,  with  tripod  and  leveling  screws,  complete $3C  oo 

\  1617.     Plain  Surveyors*  Compass,  5-inch  needle,  i4-incli  plate,  as 

above,  with  tripod  and  leveling  screws,  complete  ...    ...     35  oo 

A  1618.     Plain  Surveyors'  Compass,  6-inch  needle,  1 5-inch  plate,  as 

above,  with  tripod  and  leveling  screws,  complete 40  oo 


THE  VARIATION  COMPASS. 

The  Variation  Compass  is  constructed  on  the  same  model  as  the 
Plain  Compass,  but  has  in  addition  a  variation  plate  which  is  placed  on  com- 
pass plate  and  is  operated  by  loosening  the  clamp  screw  so  that  the  compasss 
rim  can  be  moved  in  azimuth  to  set  off  the  magnetic  variation  of  the  needle. 

A  1619.     Variation  Compass,  4-inch  needle,  13-inch  plate,  as  above, 

with  tripod  and  leveling  screws,  complete $35  oo 

A  1620.     Variation  Compass,  5-inch  needle,  14-inch  plate,  as  above, 

with  tripod  and  leveling  screws,  complete 40  oo 

A  1621.     Variation  Compass,  6-inch  needle,  15-inch  plate,  as  above, 

with  tripod  and  leveling  screws,  complete 45  oo 

Any  of  these  compasses  can  be  furnished  with  ball  and  socket  joint  and  Jacob 
staff  mounting,  instead  of  leveling  screws  and  tripod  without  extra  cost. 


QUEEN    &  CO.,   INC.,   PHILADELPHIA. 


THE  VERNIER  RAILROAD  COMPASS, 


A  1622 


QUEEN   &   CO.,   INC.,   PHILADELPHIA.  91 


THE  VERNIER  RAILROAD  COMPASS. 

The  Vernier  Railroad  Compass  is  constructed  on  the  same  model  as 
A  1615.  The  needle  is  made  in  three  different  lengths,  four,  five  and  six 
inches,  and  the  plates  are  thirteen,  fourteen  and  fifteen  inches  long  respec- 
tively. The  compass  rim  is  slightly  inclined  to  facilitate  the  reading  of  the 
needle  and  is  graduated  in  half  degrees  figured  in  quadrants.  A  variation 
plate  is  attached  and  is  operated  by  unloosening  the  clamp  screw  so  that  the 
compass  rim  can  be  moved  in  azimuth  to  set  off  the  magnetic  variations  of 
the  needle.  It  also  has  a  circle  for  reading  horizontal  angles,  graduated  into 
half  degrees,  under  the  glass  cover  of  the  compass  box,  the  vernier  of  which 
reads  to  one  minute  and  is  fastened  to  the  centre,  becoming  part  of  the  main 
socket.  A  clamp  and  tangent  screw  with  opposing  spring  is  attached  to 
facilitate  the  reading  of  the  vernier.  The  sights  are  graduated  into  half  de- 
grees on  the  edge  for  angles  of  elevation  or  depression.  The  lower  part  has 
four  leveling  screws  and  clamp  and  tangent  movement.  The  instrument  is 
readily  attached  to  the  tripod  by  a  screw  fastened  on  head  of  tripod.  The 
sights  are  detachable  and  are  packed  in  case  with  the  compass.  The  box  is 

fitted  with  plumb  bob,  screw  drivers,  wrench,  etc. 

• 

A  1622.     Vernier  Railroad  Compass,  4-inch  needle,  1 3-inch  plate,  as 

above,  with  tripod  and  leveling  screws,  complete  ...    ...  $45  oo 

A  1623.     Vernier  Railroad  Compass,  5-inch  needle,  14-inch  plate,  as 

above,  with  tripod  and  leveling  screws,  complete 55  oo 

A  1624.     Vernier  Railroad  Compass,  6-inch  needle,  i6-inch  plate,  as 

above,  with  tripod  and  leveling  screws,  complete 65  oo 


QUEEN  &  co.,  INC.,  PHILADELPHIA. 


HAND  LEVELS. 


A  1638. 

A  1638.     Locke  Hand  Level,  5-inch,  brass ,....,  $6  oo 

A  1639             Do.          do.           5-inch,  German  silver 8  oo 

A  1640.            Do.          do.           5-inch,  nickel  plated    ...    t    ...  8  oo 


A  1641. 

A  1641,     Queen  Hand  Level,  square  tube,  5-inch,  nickel  plated    .    .      4  50 

In  the  Queen  Hand  Level  the  reflector  is  an  oval-polished  platet 
crossing  the  centre  of  the  field  of  view,  so  that  the  field  appears  on  all  iout 
•Sides  of  the  reflected  bubble. 


A  1642. 

A  1642.     Abney  Level  and  Clinometer,  a  combination  of  the  "Locke 

Hand  Level,"  with  the  Clinometer,  giving  angles  of  elevation 

and  slopes;  in  wood  box $13  50 


QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


93 


A  1643. 

A  1643.     Aoney's  New  Model   Reflecting  Level   or   Pocket  'Alti- 
meter, improved,  with  compass;  in  box $18  oo 

DIRECTIONS   FOR   USE. 

When  the  height  of  any  object  is  required  to  be  taken,  a  distance 
should  be  correctly  measured  from  the  object,  say  100  feet.  This  forms  the 
•  base  line,  and  at  which  point  the  observer  would  stand;  then  direct  his 
vision  through  the  tube  of  the  level,  and  elevate  it  until  the  highest  point  of 
the  object  is  seen  bisected  by  the  horizontal  edge  of  the  reflector  within  the 
tube.  While  holding  it  steadily  in  this  position,  the  spirit  level,  which  is 
attached  to  the  axis  of  the  arc,  should  be  turned  upon  its  centre  until  the 
bubble  is  seen  reflected  in  the  mirror,  and  also  bisected  by  the  horizontal 
edge  of  reflector,  the  alignment  is  then  complete,  and  the  height  of  object 
obtained  by  reading  off  the  index  of  the  arc. 

The  arc  has  two  graduated  scales  upon  it,  one  giving  the  angular 
measurement  by  degrees,  and  subdivided  by  the  vernier  divisions  on  the 
index.  The  other  scale  is  figured  i  to  10  with  their  subdivisions,  represent- 
ing iV,  i,  YZ,  etc.,  of  the  length  of  the  measured  base^  and  is  read  off  by  the 
fiducial  edge  at  the  side  of  index.  If,  therefore,  the  edge  coincides  with 
division  4,  the  height  of  object  would  be  V±  of  the  base  line,  or  25  feet.  In 
using  the  angle  reading  scale  on  arc  the  following  tables  may  be  referred  to : 


Angle 


gradient . 


3°3o'. 
4°'     • 
4°3o'. 
5°      • 
6° 
8° 
10° 

12° 


i  in  57. 
in  38. 
in  28.6 

Angle  14° 
"   16° 
18° 

in  22.8 

11    20° 

in  19. 
in  16.2 
in  14.3 
in  12.6 

"    22° 

"   24° 

11    26° 

"    23° 

in  1  1.4 
in  9.5 
in  7.1 
in  5.6 

"   30° 

"   35° 
"   40° 

11   45° 

in  4.7 

gradient 


in  4. 
in  3.4 
in  3. 
in  2.7 
in  2.4 
in  2.2 
in  2. 
88 

73 
40 

20 


When  a  slope  or  gradient  is  required  to  be  set  out  to  any  given  angle, 
the  index  of  the  arc  should  be  set  by  reference  to  the  above  tables,  and  the 
instrument  placed  upon  the  object  to  be  inclined  ;  this  should  then  be  raised 
or  lowered  until  the  bubble  is  seen  in  the  centre  of  spirit  level,  the  required 
gradient  being  thus  given. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


CLINOMETERS. 


A  1644. 

A  1644.  Boxwood  Clinometer,  T2  inches  folding  to  6  inches,  brass 
mountings,  2  levels,  compass  and  inclination  scale,  in  leather 
case ...  $8  50 

-^64414.  Boxwood  Clinometer,  with  sights  as  illustrated,  in  leather 

case ii  50 


A  1645.  A  1645^. 

\  1645.    Clinometer  or  Slope  Level,  small,  In  morocco  box  .    ...  $800 

^  |^45/^«        Do.                  do.             large,  in  morocco  box    ....  12  oo 

\  1646.            Do.                  do.             large,  with  perpendicular  sight  15  oo 


A  1647.  A  1648. 

A  1647.     Clinometer,  of  square  frame,  with  arc  running  diagonally 

across;   in  box $12  oo 

A  1648.     Linton's  Hand-Level  and  Clinometer $20  oo 


QUEEN   &  CO.,    INC.,   PHILADELPHIA.  95 

THE  "QUEEN"   MACHINISTS1   LEVELS  OF 
PRECISION. 


A  1649. 

Spirit  Levels  are  the  most  sensitive,  and  therefore  most  important, 
appliances  for  practically  determining  horizontal  or  vertical  planes,  and  for 
measuring  small  angles.  They  replace  and  far  excel  the  plumb  line  as  for- 
merly used  for  the  same  purpose.  The  production  of  an  accurate  spirit  level 
is  a  work  requiring  much  skill  and  patience  and  knowledge  of  the  scientific 
principles  involved .  It  includes  principally  the  grinding  of  the  curve  and 
the  sealing  of  the  tube. 

The  sensitiveness  of  a  level  depends  upon  the  radius  of  curvature, 
which  in  ground  levels  is  mainly  obtained  by  the  grinding  of  the  inner  sur- 
face to  the  requisite  curve,  which  practically  is  a  difficult  operation,  requiring 
special  skill  in  its  manipulation.  The  sensitiveness  of  a  level  varying 
directly  as  the  radius  of  curvature ;  levels  ground  to  a  short  radius  give 
scarcely  any  displacement  of  the  bubble  for  a  small  variation  of  the  angle, 
while  those  of  sufficiently  long  radius  may  be  made  to  show  an  appreciable 
displacement  of  a  bubble  for  an  angular  value  of  but  a  fraction  of  second  of 
arc.  The  sensitiveness  of  levels  is  usually  stated  as  so  much  deviation  of 
the  bubble  per  single  division  of  one  French  ligne  of  2.26  mm.  in  length. 

In  furnishing  our  Machinists'  Levels  of  Precision,  we  are  prepared  to 
supply  a  level  of  any  requisite  degree  of  curvature  and,  consequently,  any 
required  degree  of  sensitiveness.  Our  Machinists'  Levels  of  Precision  are 
carefully  mounted  in  iron  case,  with  brass  top  and  accurately  planed  sur- 
faces ;  also  are  adjustable  laterally  and  vertically.  They  are  supplied  with 
short  cross  level  carefully  ground,  and  the  main  bulb  is  graduated  in  inches 
and  tenths. 

This  form  of  Spirit  Level  has  long  been  recognized  as  the  best  con- 
structed and  most  suitable  form  for  setting  up  locomotives,  stationary 
engines,  boilers,  planers,  lathes  and  all  fine  machinery,  and  is  guaranteed  to 
give  satisfaction. 

A  1649.     Machinists'  Level,  8  inches  long $800 

A  1650.  Do.  10         do.  . 10  oo 

A  1651.  Do.  12         do.  12  oo 

A  1652.  Do.  15         do.  15  oo 

A  1652^.  Do.  18         do.  18  oo 

A  1652^.  Do.  24         do.  24  oo 


QUEEN  &  CO.,  INC.,  PHILADELPHIA 


A  1653.  A  1657. 

A  1653.  High  Grade  Sextant.  As  made  for  the  U.  S.  Navy,  of  hard 
bronze,  finished  smooth  in  a  lustreless,  durable  dark  color.  The 
sextant  capable  of  measuring  an  angle  of  130  degrees.  The 
radius  of  the  instrument  measures  from  centre  of  pivot  to  out- 
side edge  of •  limb  7  inches.  Graduated  arc,  upon  silver, 
divided  to  10  minutes,  vernier  reading  to  10  seconds.  One  plain 
tube  for  sighting.  One  astronomical  telescope.  One  terrestrial 
telescope.  Two  mirrors.  Four  colored  shade  glasses.  One 
neutral  glass  to  each  telescope.  Weight  of  instrument  without 
telescope,  3^/2  pounds.  Instrument  complete  with  two  screw 
drivers  ;  two  neutral  tinted  sunshades  ;  one  extra  index  mirror  ; 
one  extra  horizon  mirror,  and  the  necessary  tools  for  adjust- 
ment. Polished  mahogany  box  with  lock  and  key.  Price,  $130  oo 
A  1654.  High  Grade  Sextant,  as  used  in  English  Navy.  Price,  $95  oo 
A  1655.  High  Grade  Surveyors'  Sextant.  As  made  for  the  U.  S. 
Navy  of  hard  bronze,  finished  smooth  in  a  lustreless,  durable, 
dark  color.  The  sextant  capable  of  measuring  an  angle  of  130 
degrees.  The  radius  of  the  instrument  measures  from  centre  of 
pivot  to  outside  of  limb  5.72  inches.  Graduated  arc,  upon  sil- 
ver, divided  to  20  minutes,  vernier  reading  to  30  seconds.  One 
plain  tube  for  sighting  ;  one  astronomical  telescope  ;  one  terres- 
trial telescope .  Two  mirrors,  four  colored  shade  glasses.  One 
neutral  glass  to  each  telescope.  Weight  of  instrument  without 
telescope,  2.^/2,  pounds.  Instrument  complete  with  two  screw 
drivers  :  two  neutral  tinted  sunshades  ;  one  extra  index  mirror  ; 
one  extra  horizon  mirror,  and  the  necessary  tools  for  adjust- 
ment. Polished  mahogany  box  with  lock  and  key.  Pric4  $no  oo 
A  1656.  Surveyors'  Sextant,  as  used  in  English  Navy.  .  Price,  $62  oo 
A  1657.  high  Grade  Octant.  As  made  for  the  U.  S.  Navy,  of  hard 
bronze,  finished  smooth  in  a  lustreless,  durable  dark  color. 
The  octant  capable  of  measuring  an  angle  of  100  degrees.  The 
radius  of  the  instrument  measures  from  centre  of  pivot  to  out- 
side edge  of  limb  7  inches.  Graduated  arc,  upon  silver,  divided 
to  20  minutes,  vernier  reading  to  30  seconds.  One  plain  tube 
for  sighting;  one  terrestrial  telescope.  Two  mirrors;  four  col- 
ored shade  glasses.  One  neutral  glass  to  telescope.  Weight 
of  octant  without  telescope,  2^  pounds.  Instrument  complete 
with  two  screw  drivers ;  two  neutral  tinted  sunshades  ;  one 
extra  index  mirror  ;  one  extra  horizon  mirror,  and  the  necessary 
tools  for  adjustment.  Polished  mahogany  box  with  lock  and 
key.  Price,  $90  oo 

A  1658.     Octant,  as  used  in  English  Navy.  Price,  $32  oo 


QUEEN   &  CO.,    INC.,   PHILADELPHIA. 


POCKET  SEXTANT. 


A  1659. 

A 1 659.  Pocket  Sextant,  divided  on  silver  to  30  minutes,  vernier 
reading  to  i  minute,  with  telescope,  2  neutral  glasses,  reading 
lens,  and  micrometer  tangent  screw.  Metal  box  3  inches  in 
diameter  by  i^  inches  high,  in  leather  sling  case.  Price,  $42  oo 


POCKET  ALT-AZIMUTH. 


A  1660. 

A  1660.  Pocket  Alt-Azimuth,  for  travelers  and  military  surveyors, 
6^  inches  long,  2J2  inches  diameter,  iyb  inches  thick,  weight, 
13  ounces  ;  in  morocco  case.  Price,  $47  oo 

Altitudes,  azimuths,  compass  bearings,  clinometer  degrees  and  levels 
are  all  available  by  this  convenient  and  highly  reliable  little  instrument. 
The  advantages  of  its  use  have  been  so  increased  by  the  recent  addition  of 
an  excellent  telescope  as  to  make  it  perfect  for  the  various  purposes  to  which 
it  can  be  applied. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


ARTIFICIAL  HORIZON. 


A  1661. 


A  1661.  Mercurial  Horizon,  of  boxwood,  with  silver-plated  copper 
bowl ;  bottle  of  boxwood  for  mercury,  brass  rectangular  roof 
with  glass  covers  made  of  parallel  glass.  Complete,  in  case. 

Price,  $45  oo 


AMSLER  PLAN  I  METER. 


A  1663. 

1663.     Amsfcer  Planimeter,  for  engineers.     In  morocco  case,  with 

instructions.  Price,  $30  oo 


QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


HELIOGRAPHS. 


A  1665. 


A  1665.  Heliograph.  The  above  illustration  shows  the  improved 
Heliograph  as  used  by  the  U.S.  Army  for  military  signaling 
purposes.  The  heliograph  equipment  consists  of  i  sun 
mirror,  i  station  mirror,  i  screen,  i  sighting  rod,  i  screw 
driver,  all  enclosed  and  packed  in  leather  case.  One  minor 
bar  in  leather  pouch  attached  to  above  case.  Two  tripod 
stands  in  skeleton  leather  case.  One  copy  "  Military  Signal- 
ing," by  Capt.  Albert  Gallup.  Price,  $60  oo 


100 


QUEEN   &   CO.,    INC.,    PHILADELPHIA. 


.  A  1668. 


A  1672. 


A  1673. 


A  1668.  Cross  Staff  Head,  for  turning  right  angles,  in  case,  2^ 

inches .  .  ... $3  oo 

A  1669.  Cross  Staff  Head,  for  turning  right  angles,  in  case,  3 

inches 3  50 

A  1670.     Cross  Staff  Head,  with  magnetic  compass,  3  inches,  needle 

1 24  inches 4  75 

A  1671.     Cross  Staff  Head,  with  vertical  axis  and  divided  circle,  £o 

take  angles  3^  inches .*...........     12  oo 

A  1672.     Reflecting  Hand  Mirror,  for  turning  right  angles    ....      5  oo 

A  1673.     Rectangular     Prism,    for    right    angles,     2>^xi^(xi^ 

inches,  in  morocco  case .' 5  oo 

A  1674.  Surveyors'  Angle  Mirror,  for  right  angles,  with  a  small 
plumb  bob.  Size  of  instrument  when  packed,  3^x2x1^ 
inches .  .  .  *  V  ......  .  .  .  .  7  50 

A  1675.     Double   Prism,  to  take  angles  of  90  and  45  degrees,  in 

morocco  ca"se  .  10  oo 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


101 


PEDOMETERS  AND  ODOMETERS* 


A  1688. 


A  1686. 


Pedometers  ate  pocket  instruments  for  measuring  distance  traversed 
in  walking — the  number  of  miles  being  registered  by  a  mechanism,  enclosed 
in  a  nickel  plated  watch  casing,  and  operated  by  the  motion  of  the  body. 
Directions  accompany  each  instrument.  The  following  are  of  the  best  make 
only. 

A  1678.     Pedometer,  with  dial  divided  to   12  miles  and  reading  to 

quarters  ..... $4  50 

A  1679.     Pedometer,   as  above,  with    mechanism    rendered    visible 

through'  glass  back 5  oo 

A  1680.  Pedometer,  dial  divided  to  10  miles  and  reading  to  quar- 
ters, with  inner  dial  recording  100  miles 6  oo 

A  1681.     Pedometer,   as   above,   with   mechanism   rendered   visible 

through  glass  back 6  50 

A  1682.  Pedometer,  dial  divided  to  1,760  j^ards  and  reading  to 
halves,  with  inner  dial  recording  50  miles,  mechanism  rendered 
visible  through  glass  back  .  .  6  oo 


QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


A  1683.  Passometer,  designated  to  record  the  number  of  steps,  dial 
divided  to  100,  with  two  inner  dials,  registering  respectively, 
1,000  and  25,000  steps,  mechanism  rendered  visible  through 
glass  back ;  highly  commendable $6  oo 

A  1684.     Pedometer,  similar  to  A   1679,  with  crown   for  instantly 

setting  hand  back  to  o 6  oo 

A  1685.     Pedometer,  similar  to  A    1681,   with  crown  for  instantly 

setting  hand  back  to  o 7  50 

A  1686.     Passometer,  similar  to   A   1683,  with  crown  for  instantly 

setting  hand  back  to  o     . 7  oo 

A  1687.     Passometer,  100,000  steps,  with  crown  for  instantly  setting 

hand  back  to  o  .  .    ,  8  oo 


A  1688.  A  1689. 


A  1688.  The  Queen  Odometer  is  an  instrument  for  ascertaining  the 
number  of  miles  traversed  by  a  carriage  or  wagon,  the  revoVii 
tions  of  the  wheel  being  registered,  and  the  miles  computed  by 
an  accompanying  table.  Odometer,  recording  100,000  revolu- 
tions, in  sole  leather  case,  with  strap  for  securing  it  to  the 
wheel $15  oo 

A  1689.  The  Bell  Odometer  is  designed  to  register,  record  and 
announce  distances  traveled  by  buggies  or  other  wheeled 
vehicles.  Attached  to  the  axle,  it  is  operated  by  a  steel  pin 
driven  into  the  hub.  and  is  automatic,  neat  and  reliable. 
Price,  complete 5  °° 


QUEEN   &   CO.,    INC.,   PHILADELPHIA. 


103 


CHESTERMAIM'S  TAPES, 


CHESTERMAIM'S  METALLIC  TAPE 
MEASURES. 

These  tapes  are  made  of  linen  thread,  in- 
terwoven with  fine  brass  wrire,  not  so  liable  to 
stretch  as  the  usual  linen  tape  and  better  cal- 
culated to  withstand  the  effect  of  moisture. 
They  are  in  substantial  leather  cases. 


A  1690.  Metallic  Tapes,  24  feet  long,  in  icths  or  i2ths,  each  .    .    .  $i  80 

A  1691.  Do.             33               do.                     do.  ...     2   10 

A  1692.  Do.             40               do.                     do.  ...     2  30 

A  1693.  Do.             50               do.                     do.  ...     2  60 

A  1694.  Do.             66               do.                     do.  .    .    .    3  oo 

A  1695.  Do.             70               do.                     do.  ...     3  20 

A  1696.  Do.             75               do.                     do.  ...    3  30 

A  1697.  Do.             80               do.                     do.  ...    3  70 

A  1698.  Do.           100              do.                    do.  ...    4  20 

CHESTERMAN'S   METALLIC  TAPES  WITHOUT  BOXES. 

A  1699.  Metallic  Tape,   50  feet  long,  in  loths  or  i2ths,  each  .    .    .  $i  50 

A  1700.  Do.           100               do.                     do.  ...    2  90 


CHESTERMAN'S  STEEL  TAPE   MEASURES. 

Steel  tape  measures  ;  all  steel,  to  wind  up  in  a 
box,  same  as  linen  measures ;  the  most  accurate, 
durable  and  portable  measures. 


A  1701.     Steel  Tape,  25  feet  long,  in  loths  or  i2ths,  each $4  50 


A  1702. 

Do. 

33 

do. 

A  1703. 

Do. 

40 

do. 

A  1704. 

Do. 

50 

do. 

A  1705. 

Do. 

66 

do. 

A  1706. 

Do. 

75 

do. 

A  1707- 

Do. 

100 

do. 

do. 
do. 
do. 
do. 
do. 
do. 


5  20 

6  oo 

7  20 
9  20 

10  40 

12    80 


104  QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


EDDY'S  TAPES. 


Eddy's  Improved  Standard  Steel  Tapes,  ^  inch  wide,  in  leather -covered 
cases,  flush  handle,  metal  lined. 


A  1708.    Steel  Tape,  25  ft.  long,  in  zoths,  i2ths  or  metric  measure,  each  $5  oo 


A  1709. 

Do. 

33 

A  1710. 

Do. 

40 

A  1711. 

Do. 

50 

A  1712. 

Do. 

66 

A  1713. 

Do. 

•     75 

A  1714. 

Do. 

IOO 

do. 
do. 
do. 
do. 
do. 
do. 


do. 
do. 
do. 
do. 
do. 
do. 


do. 
do. 
do. 
do. 
do. 
do. 


5  50 

7  oo 

8  oo 
10  oo 

12    00 

15  oo 


•  Paine 's  Patent  Standard  Steel  Tapes,  in  iron  cases,  brass  bound,  mo- 
rocco covered,  improved  handles,  and  are  detachable  from  case,  and  are 
furnished  with  detachable  rings  to  avoid  breakage. 


A  1715.    .Steel  Tape,  25  ft.  long,  in  ioth 
A  1716.            Do.         33                do. 
A  1717-            Do.         50                do. 
A  1718.             Do.         66                 do. 
A  1719,             Do.         75                 do. 
A  1720.            Do.       100                 do. 

is  or  i2t]is,  each  . 

.  $t    5O 

do. 

4    SO 

do. 

v3  oo 

do. 

.    ....    6  oo 

do. 

8  oo 

do. 

.    12    OO 

QUEEN   &   CO.,    INC.,    PHILADELPHIA. 


105 


RELIABLE"  STEEL  TAPES. 


"Reliable"  Patented  Steel 
Tapes,  2/8  inch  wide,  in  hard 
leather  cases,  nickel-plated 
trimmings,  with  double  fold- 
ing flush  handle,  opened  by 
pressing  small  pin  or  button 
on  opposite  side,  graduated  on 
the  back  with  links  and  poles. 
Extra  graduations  of  feet  on 
one  side,  meters  on  the  other 
or  feet  and  i2th  on  one  side 
and  loths  on  other  at  2)4c. 
per  foot  to  list  price. 

A  1721.     Steel  Tape,  25  feet  long,  in  loth  or  i2th,  each $4  50 

5  20 

6  oo 

7  20 
9  20 

10  40 

12    80 


A  1722. 

Do. 

33 

do. 

do. 

A  1723. 

Do. 

40 

do. 

do. 

A  1724. 

Do. 

50 

do. 

do. 

A  1725. 

Do. 

60 

do. 

do. 

A  1726. 

Do. 

75 

do. 

do. 

A  1727. 

Do. 

100 

do. 

do. 

"  Reliable"  Frame  Steel  Tapes,  ^  inch  wide,  nickel-plated  frames 
and  trimmings,  with  double  folding  flush  handle,  opened  by  pressing  small 
pin  or  button  on  opposite  side,  graduated  on  the  back  with  links. 

A  1728.  Steel  Tape,  50  feet  long,  in  loth  or  i2th,  each $7  50 

A  1729.  Do.  66  do.  do.  9  50 

A  1730.,          Do.  75  do.  do.  n  50 

A  1731.  Do.         loo  do.  do.  13  50 


io6 


QUEEN  &  CO.,   INC.,   PHILADELPHIA. 


STEEL  TAPES. 


"  Rival"    Steel   Tapes, 
inch  wide,  nickel-plated  steel 
case,  flush  handle,  graduated 
one  side  only. 


A  1732.     Steel  Tapes,  25  feet  long,  in  loths  or  i2ths,  each $3  25 

A  1733-  Do.  50  do.  do.  4  oo 

A  1734-  Do.           75                 do.                 do.                   .....     5  25 

A  1735-  Do.         100  do.  do.  6  75 


Metallic  Tapes,  fyi  inch 
wide,  hard  leather  cases,  with 
patent  double  folding  flush 
handle,  made  of  best  woven 
linen,  with  metallic  warp, 
graduated  on  back  in  links. 


^^ 
A  1736.     Metallic  Tapes,  25  feet 

long,  in  roths  or  i2ths,  each 

A  1737- 

Do. 

33 

do. 

do. 

A  1738. 

Do. 

40 

do. 

do. 

A  1739. 

Do. 

50 

do. 

do. 

A  1740. 

Do. 

66 

do. 

do. 

A  1741. 

Do. 

75 

do. 

do. 

A  1742. 

Do. 

IOO 

do. 

do. 

t>2  10 

2  40 

2  60 

2  90 

3  30 

3  60 

4  50 


QUEEN   &   CO.,   INC.,    PHILADELPHIA. 

POCKET  STEEL  TAPES. 

GERMAN   SILVER  CASES,  SPRING  WIND,  WITH    STOP. 


107 


A  1  743  A.     Pocket  Tape,  ^  in.  wide 

,  36  in.  long,  in  1  6ths,  each   .    .    .  $i  25 

A  17436. 

Do. 

%       do. 

48  in.        do. 

do.            ... 

i  40 

A  I743C- 

Do. 

%       do. 

60  in.        do. 

do.            .   .    . 

i   50 

A  I743D. 

Do. 

#       do. 

72  in.        do. 

do.            ... 

i  75 

A  I743E. 

Do. 

^       do. 

7  ft.         do. 

do.            ... 

2    OO 

A  I743F. 

Do. 

TV       do. 

9  ft.         do. 

do.            ... 

2    25 

A  17430. 

Do. 

A       do. 

1  2  ft.         do. 

do.            .    .    , 

3  oo 

A  I744A. 

Do. 

^       do. 

36  in.  long,  in 

i6ths  and  meter, 

i  50 

A  I744B. 

Do. 

#       do. 

48  in.        do. 

do. 

i  75 

A  17440. 

Do. 

#       do. 

60  in.        do. 

do. 

2    00 

A  I744D. 

Do. 

%       do. 

72  in.        do. 

do. 

2    25 

A  I744E. 

Do. 

X       do. 

7  ft.         do. 

do. 

2    50 

A  I744F. 

Do. 

^       do. 

9  ft.         do. 

do. 

2  75 

A  I744G. 

Do. 

#       do. 

I  2  ft.             do. 

do. 

3  50 

RELIABLE   JUNIOR 

POCKET  STEEL 

TAPE. 

Reliable  Junior  Steel  Tape, 
^  inch  wide,  hard  leather 
cases,  with  patent  double 
folding  flush  handle,  gradu- 
ated one  side  only. 


A  I745R.     Steel  Tape,  25  feet  long,  in  icths  or  i2ths,  each 
A  I745R-  Do.  50  do.  do. 


4  oo 

5  oo 


io8 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


QUEEN  STEEL  TAPE  CHAINS  ON  PATENT  REEL. 

NICKEL-PLATED. 


Queen  Steel  Tape  Chains  on  Patent  Reel.  It  allows  the  entire  tape 
open  to  dry,  and  with  it  the  tape  can  be  reeled  or  unreeled  as  easily  and 
readily  as  the  linen  or  metallic  tapes  in  cases.  Also  the  tape  can  be  easily 
detached  and  used  without  the  reel.  When  in  use,  in  mines  or  crowded 
thoroughfares,  it  is  used  the  same  as  tapes  in  cases.  All  sizes  except  200 
and  300  feet  can  easily  be  carried  in  any  average  pocket. 


A 

i746A. 

IOO 

feet  long,  every 

foot.    End  feet  in  tenths, 

Plain. 
$500 

Nickel 
Plated. 

$600 

Alumi- 
nium 
Plated. 

$700 

A 

17468. 

IOO 

do. 

do 

do.         inches, 

5 

00 

600 

7  oo 

A 

I746C. 

IOO 

do. 

every 

5  feet. 

do.         tenths, 

4 

OO 

5 

00 

6  oo 

A 

I746D. 

IOO 

do. 

every 

5  feet. 

do.         inches, 

4 

oo 

5 

oo 

6  oo 

A 

1  747  A. 

66 

do. 

every 

link 

- 

oo 

6 

oo 

6  50 

A 

I747B. 

66 

do. 

in  Rods  and 

tenths  of  a  Rod   . 

5 

6 

00 

650 

A 

I747C. 

66 

do. 

every 

5  links 

.  Ea.  end  every  link 

4  oo 

5 

00 

550 

A 

I748A. 

50 

do. 

every 

foot. 

End  feet  in  tenths, 

4 

00 

5 

oo 

550 

A 

17488. 

50 

do. 

every 

foot. 

do.         inches, 

5 

00 

5 

oo 

550 

A 

17480. 

60 

do. 

every 

5  feet. 

do.         tenths, 

3 

00 

4 

00 

450 

A 

i748D. 

50 

do. 

every 

5  feet. 

do.         inches, 

3 

00 

4  oo 

450 

A 

I749A. 

33 

do. 

every 

link  . 

,    . 

3 

00 

4 

00 

450 

A 

17498. 

33 

do. 

every 

5  links 

.  Ea.  end  every  link 

2 

50 

3 

oo 

350 

A 

I750A. 

200 

do. 

every 

foot. 

End  feet  in  tenths, 

7 

50 

9  oo 

1050 

A 

17508. 

200 

do. 

every 

foot. 

do.         inches, 

7 

50 

9 

00 

1050 

A 

17500. 

200 

do. 

every 

5  feet. 

do.          tenths, 

6 

GO 

7 

50 

9  oo 

A 

I750D. 

200 

do. 

every 

5  feet. 

do.         inches, 

6 

oo 

7 

50 

9  oo 

A 

i75iA. 

300 

do. 

every 

ft.  End  ft.  in  loths  or  ins. 

1000 

12 

00 

14  oo 

A 

17518. 

300 

do. 

every 

5ft. 

do. 

8 

00 

10 

00 

12  00 

A 

I752A. 

400 

do. 

every 

foot. 

do. 

12 

50 

15 

oo 

1750 

A 

17528. 

4OO 

do. 

every 

5  feet. 

do. 

10 

00 

12 

50 

1500 

A 

I753A. 

500 

do. 

every 

foot. 

do. 

15 

00 

18 

00 

21  00 

A 

I753B. 

500 

do. 

every 

5  feet. 

do. 

12 

00 

15 

oo 

1800 

A 

I7S4A. 

IOO 

feet,  Electric  Reel,  without  Tape  

I  50 

A 

y  *7" 

17548. 

2OO 

do.                        do.            

2  OO 

A  . 

*zc>rt 

do. 

do  

2  50 

Detachable  Handles, 

per  pair 

^0 

QUEEN   &  CO.,   INC.,   PHILADELPHIA. 

ENGINEERS'  AND  SURVEYORS'  CHAINS. 


109 


A  1761. 


A  1760. 

Surveyors*  Iron  Chain,  W.  G.  9,  33  feet,  2  poles,  oval  rings 

$2   OO 

A  1761. 

Do.                     do.    8,  33  feet,  2 

do. 

2    50 

A  1762. 

Do.                     do.    7,  33  feet,  2 

do. 

3  oo 

A  1763. 

Do.                     do.    9,  66  feet,  4 

do. 

3  50 

A  1764. 

Do.                     do.    8,  66  feet,  4 

do. 

4  50 

A  1765. 

Do.                     do.    7,  66  feet,  4 

do. 

5  50 

A  1766. 

Surveyors*  Steel  Chain,  W.  G.  12,  33  feet, 

brazed  links 

and  rings 

5  50 

A  1767. 

Surveyors*  Steel  Chain,  W.  G.   12,  66  feet, 

brazed  links 

and  rings  -    

IO   OO 

A  1768. 

Engineers*  Iron  Chain,  W.  G.  7,  50  feet,  oval 

rings  .    .   . 

4  oo 

A  1769. 

"                  "                  "      7,  100  "            "           ... 

6  oo 

A  1770. 

Engineers*  Steel  Chain,  W.  G.   12,  50  feet, 

brazed  links 

and  rings      

6  oo 

A  1771. 

Engineers*  Steel  Chain,  W.  G.  12,  100  feet, 

brazed  links 

II    OO 

METER   AND   VARA   CHAINS. 

A  177*. 

Steel  Chain,  \V.  G.  10,  10  meter,  oval  rings 

$T>  so 

/  /  O  * 

A  1774. 

Do                do      10    15     do            do 

*r  O        «J 

5  °° 

i   i  /  /*!• 
A  1775. 

Do                do.     10,  20     do.           do. 

6    2<> 

1  •  /  jj* 

A  1776. 

Do.               do.     10,  10     do.     brazed  links 

and  rings    . 

v/ 

5  50 

A  1777- 

'Do.               do.     10,  15     do.               do. 

do. 

7  50 

A  1778. 

Do.               do.     10,  20    do.               do. 

do. 

10   00 

A  I77O. 

Do                 do.     10,  10  varas,  oval  rings 

7     SO 

k  •  /  /  VB 

A  1780. 

Do                do       10    20     do           do 

O     J 

6  50 

A  1781. 

Do.               do.     10,  10    do.     brazed  links 

and  rings    . 

5  50 

A  1782. 

Do.               do.     10,  20    do.              do. 

do. 

10   00 

no 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 


MARKING  PINS. 


A  1793- 


A  1791, 


A  1795- 


A  1790. 
A  1791. 
A  1792. 
A  1793- 
A  1794- 
A  1795- 


Marking  Pins,  No,  4  iron  wire,  ii  in.  set $i  25 

2  oo 

3  °° 
6  oo 


Do. 

Do. 

Do. 

Canvas  Case, 
Stake  Tacks, 


No.  6  steel  wire,  n  in.  set 

No.  6  steel  wire,  n  in.  set,  weighted  point, 
tempered  steel,  n  in.  set,        ^n-  wide     .    . 


with  shoulder  straps,  for  pins 2  oo 

sralvanized,  VA  ib.  boxes  .  30 


PLUMB  BOBS. 


A  1800. 


A  1808. 


A  1806. 


A 
A 
A 
A 
A 
A 
A 

1800. 
1801. 

1802. 
1803. 
1804. 
1805. 
1806. 

Brass  Plumb  Bob,  6  ounces,  steel  point, 
Do.         do.        9     do.             do. 
Do.         do.       12     do.             do. 
Do.         do.       18     do.             do. 
Do.         do.      24     do.             do. 
Do.         do.      36     do.             do. 
Patent  Adjustable  Plumb  Bob,  8  ounces 

screw  cap.    .    .    . 
do.         ... 
do.         .    .    . 
do.         .    .    . 
do.         ... 
do.         .    .  % 

$i 

2 
2 
2 

3 

4 

T 

50 
00 

25 
50 

OO 

75 

A 

1807. 

Do                                do         1  2     do 

o 

OC5 

A 
A 

1808. 
1809. 

Do.                               do.        12     do. 
Plumb  Bob  Cord,  best  linen,  per  yard 

concealed  reel  .   . 

2 

50 
re? 

A 

1810. 

Do.         do.     braided  silk,  per  vard  . 

OS 

Nos.  A  1806  and  A  1807  are  constructed  with  a  reel  at  the  upper  end, 
upon  which  the  line  may  be  kept,  and  by  dropping  the  bob  with  a  slight 
jerk,  while  the  ring  is  held  in  the  hand,  any  length  of  line  may  be  reeled  off. 
A  spring,  which  has  a  bearing  on  the  reel,  will  check  and  hold  the  bob 
firmly  at  any  desired  point  of  the  line. 

No.  A  1808.  Patent  Adjustable  Plumb  Bob,  with  concealed  reel, 
around  which  the  string  is  wound  by  turning  the  milled  head  on  top.  The 
friction  upon  the  reel  within  will  hold  the  bob  at  any  desired  point  of  the  line. 


QUEEN   &  CO.,    INC.,   PHILADELPHIA.  in 

VERY  ACCURATE 

POCKET  ANEROID  BAROMETERS. 


COMPENSATED  AND  SPECIALLY  TESTED  AND  ADJUSTED  FOR 

ENGINEERS'   USE. 


These  Aneroids  have  movable  altitude  scales,  with  silver  enameled  dials, 

and  are  in  morocco  cases. 


13500.  13505. 

Plain  Pocket  Aneroid,  iV4  in.  diameter $15  oo 

Do.                 do.        2}^  in.       do 17  oo 

Do.                 do.        i^  in.      do.      with  thermometer   .  2000 

Do.                 do.         $l/>  in.                      do.  21  oo 

Pocket  Mountain   Aneroid,  compensated  for  temperature, 

i^  in.  diameter,  with  altitude  scale  to  3000  feet.    ....  20  oo 

Do.                             do.                           5000  feet 20  oo 

Do.                             do.                       10,000  feet 21  oo 

Do.                             do.                       15,000  feet.    .  *.   .    .  24  oo 

Do.                              do.                        20,000  feet 27  oo 

Pocket   Mountain   Aneroid,  compensated  for  temperature, 
same  as  13,505,  2%  inches  diameter,  with  altitude  scale  to 

3000  feet 20  oo 

Do.                             do.                           5000  feet 20  60 

Do.                             do.                        10,000  feet.    .    .    ,    .  21  oo 

Do.                             do.                        15,000  feet 24  oo 

Do.                             do.                        20,000  feet 27  oo 


112 


QUEEN   &   CO.,    INC.,    PHILADELPHIA. 


GEOLOGICAL  ANEROIDS, 


13515- 

Front. 

!35'5'     Geological  Aneroid,  compensated  for  temperature,  silvered 
metal  dial,  with  needle  compass  at  back,  2^  inches  diameter, 
in  leather  sling  case,  with  altitude  scale  to  5000  feet    ....  $30  oo 
13516,  Do.  do.  10,000  feet    ....    31  oo 

135*7*  Do.  do.  15,000  feet    ....    33  50 


13520. 


13520. 


Geological  Aneroid,  compensated  for  temperature,  with  sil- 
vered metal  dial,  5  in.  diameter,  in  mahogany  open  face  case, 
with  leather  strap,  with  altitude  scale  to  3,000  feet   .    . ...    .    .  $33  oo 

I352J.  Do.  do.  5,ooo  feet    .....    33  oo 

13522.  Do.  do.  io,oco  feet 35  oo 

•3523-  Do.  do.  15,000  feet 37  oo 

13524-  Do.                         do.                 with  thermometer,  altitude 
scale  to  3000  feet  .    , 35  oo 

13525-  Do.  do.  5,ooo  feet   .    .    .    .    .    35  oo 

13526.  Do.  do.  10,000  feet 37  oo 

13527.  Do.  do.  15,000  feet 39  oo 


QUEEN   &   CO.,   INC.,    PHILADELPHIA.  113 

SURVEYING  AND  MINING  ANEROIDS. 


13530- 

1353°'     Surveying  Aneroid,  5  in.  diameter,  compensated  for  tem- 
perature, silvered  metal  dial,   graduated   to  hundredths, 
and  reading  by  vernier  to  single  feet,  with  magnifier,  in 
leather  sling  case,  with  altitude  scale  to  5000  feet  ....  $50  oo 
1353'-  Do.  do.  10,000  feet       ...    55  oo 

13532.  Do.  do.  15,000  feet  ....    60  oo 

'3534-     Mining  Aneroid,  same  as  13,530,  but  arranged  to  register 

2000  feet  below  sea  level  to  4000  above .    .     50  oo 

The  Surveying  and  Mining  Aneroid  has  been  designed  and  con- 
structed specially  for  the  use  of  surveyors  and  engineers,  for  the  purpose  of 
readily  ascertaining  slight  variations  in  gradients,  levels,  etc.,  and  from  its 
extreme  sensitiveness  will  be  found  of  considerable  utility  in  mining  and 
surveying  work  generally. 

Besides  extreme  sensitiveness,  the  specialty  claimed  for  this  instru- 
ment is  an  arrangement  of  the  scale  of  altitudes  which  admits  'of  subdivis- 
ion by  a  vernier,  hitherto  impracticable,  owing  to  the  altitude  scale  in  or- 
dinary use  being  a  gradually  diminishing  one,  to  which  a  Vernier  cannot  be 
applied.  In  the  present  instrument  the  action  has  been  so  adjusted  as  to 
give  accurate  readings  upon  a  regular  scale  of  altitudes,  the  barometrical 
scale  of  inches  having  been  made  progressive  so  as  to  afford  the  correct 
relative  readings  with  the  scale  of  altitudes. 

For  mining  purposes  the  entire  circle  of  the  dial  is  graduated  to  rep- 
resent 6  inches  of  the  mercurial  column,  i.  e.,  from  27  inches  to  33.  This 
scale  will  register  about  2000  feet  below  sea-level  to  4000  feet  above ;  the 
finest  divisions,  hundredths  of  the  altitude  scale,  represent  10  feet  measure- 
ments, which  can  be  again  subdivided  by  the  vernier  scale  to  single  feet. 
The  vernier  scale  is  moved  by  a  rack- work  adjustment,  and  a  magnifying 
lens  which  rotates  on  the  outer  circumference  of  the  instrument  facilitates 
the  reading  of  minute  quantities. 

For  surface  surveying  purposes,  where  it  is  not  required  to  be  used 
below  sea-level,  the  instrument  is  made  with  the  scale  divided  from  25  to  31 
inches,  thus  giving  an  altitude  scale  of  5000  feet  above  sea -level  only,  and 
with  this  open  scale  and  the  assistance  of  the  vernier,  the  same  minnte 
readings  can  be  easily  taken. 


H4  QUEEN  &  CO.,  INC.,  PHILADELPHIA. 


ANEMOMETERS. 

FOR  MEASURING  THE  VELOCITY  OF  CURRENTS  OF  AIR  IN   COAL 

MINES,  AND   VENTILATORS,   FLUES,   ETC.,  OF 

PUCLIC  BUILDINGS. 


The  Anemometer,  an  instrument  invented  for  the  purpose  of  measur- 
ing the  rate  at  which  air  moves  in  mines  and  ventilation  passages,  is  now  an 
indispensable  adjunct  of  the  former,  the  mining  laws  of  most  States  requir- 
ing that  a  certain  number  of  cubic  feet  of  air  shall  be  passed  to  the  air- ways, 
and  the  anemometer  furnishing  the  most  convenient  and  satisfactory  mode 
by  which  tne  amount  of  air  passing  can  be  determined. 


No.  14,500. 


No.  14,505. 


14,500.     Bi rain's  Anemometer,  6  inches  diameter,  reading  to  ten 

million  feet,  with  disconnector,  Fig.  i $40  oo 

14,561.  Biram's  Anemometer,  5  inches  diameter,  same  as  14,500  .  39  oo 
14,502.  Biram's  Anemometer,  3  inches  diameter,  same  as  14,500  .  37  oo 
I4»505-  Biram's  Anemometer,  12  inches  diameter,  reading  to  ten 

million  feet,  with  disconnector 45  °° 

14,506.-  Biram's  Anemometer,  6  inches  diameter,  same  as  i4>5°5>  4°  °o 
14,507.  Biram's  Anemometer,  4  inches  diameter,  same  as  14,505,  37  50 


QUEEN   &  CO.,    INC.,   PHILADELPHIA. 


115 


14508. 

14508.  Bi ram's  Anemometer,  6   inches  diameter,  reading  to  1000 

feet,  with  disconnector    .....*,.... $25  oo 

14509.  Bi  ram's  Anemometer,  6  inches  diameter,  reading  to  1000 

feet,  without  disconnector 22  50 

14510.  Biram's   Anemometer,  4  ins.  diameter,  reading  to  100  feet,  20  oo 

14511.  Do.  same  as  above,  with  disconnector,  22  50 

14512.  Do.  3  ins.  diameter,  reading  to  1000  feet,   1500 


14515- 

14515.  The  Portable  Air  Meter,  diameter  of  fan  wheel  2^  inches, 
with  disconnector,  which  is  extensively  used  for  testing  the 
ventilation  of  hospitals,  schools  and  public  buildings  ;    forms 
also   an   admirable  pocket   anemometer    for  tourists.       The 
indications  are  obtained  by  the  revolution  of  a  series  of  fans 
(similar  to  those  of  Biram's  Anemometer)  acting  first  upon  a 
long  hand  capable  of  recording  the  velocity  of  fifty  feet  per 
minute  on  the  large  dial,  divided  to  100  feet,  and  then  success- 
ively, by  a  train  of  wheels  on  the  indices  of  five  smaller  dials, 
recording  respectively  100,  1000,  10,000,  100,000  and  10,000,- 

ooo  feet,  or  1893  miles ..........  $3°  °° 

14516.  Air  Meter,  some  as  preceding,  but  reading  only  to  1000  feet,    25  oo 

14517.  Watch    Anemometer,    very    small    and    sensitive,   outside 
dimensions  2^  ins.,  in  white  metal  hunting  case  .    .....    4000 

14518.  Watch  Anemometer,  same  as  above,  in  silver  hunting  case,  -45  oo 


QUEEN   &  CO.,   INC.,    PHILADELPHIA. 


POCKET  MAGNIFIERS. 


A  205 i . 


A  20101. 


Magnifiers,  folding,  oval  shape,  in  rubber  case  with  i  lens. 
A  2050.     Magnifier,  24 -inch  diameter  ......... 


A  2056. 
A  2062. 
A  2068. 
A  2074. 
A  2078. 


Do. 
Do. 
Do. 
Do. 
Do. 


do. 
do. 
do. 
do. 
do. 


Magnifiers,  folding,  oval  shape,  in  rubber  case,  with  2  lenses. 
A  2051.     Magnifier,  y§  and    ^-inch  diameter    ...... 


A  2057. 
A  2063. 
A  2069. 
A  2075. 
A  2079. 


Do. 
Do. 
Do. 
Do. 
Do. 


and  i 
and  i 
and  i 
and  i 
and  2 


do. 
do. 
do. 
do. 
do. 


Magnifiers,  folding,  bellows  shape,  in  rubber  case,  with  i  lens. 

A  20101.     Magnifier,  fy-inch  diameter 

A  20110.  Do.         fa         do.  

A  20119.  Do.       i  do. 


.Magnifiers,  folding,  bellows  shape,  in  rubber  case,  with  2  lenses. 

A  20102.     Magnifier,  s/8  and    24 -inch  diameter 

A  201 1 1.  Do.        Y^  and    fa       do.  

A  20121.  Do.        ?A  and  i  do.  .... 


30 
40 
60 
70 
90 
16 


50 

65 

85 

i  10 

1  65 

2  15 


40 
50 
60 


60 

75 
i  oo 


QUEEN   &   CO.,    INC.,    PHILADELPHIA. 


117 


CLEVELAND 


CaseAve 
Wilson  Ave. 


Willoughby.. 
.Reynolds... 

Meutor. 
HUSLEY 


The  above  cut  represents  Fig.  i,  the  "  Speed  Protractor,''  as  set  at  a 
speed  angle  of  25  miles  per  hour,  and  part  of  a  Chart.  Fig.  2  represents  the 
lower  head,  C,  with  the  speed  scale,  G,  engraved  on  it.  Fig.  3  is  a  cross 
section  of  the  lower  head,  C.  the  upper  and  movable  head,  B,  and  part  of 
the  blade,  A.  The  blade,  A,  is  42  inches  long,  made  of  hard  rubber  and 
backed  with  mahogany  wood.  The  two  heads,  B  and  C,  are  made  of  steam- 
dried  satin-wood  and  faced  with  ebony.  Dimensions  of  lower  head,  C,  4x15 
inches  ;  of  upper  head,  B,  2^x14)^  inches.  D,  E,  F,  Fig.  3,  represent  the 
fixed  brass  pivot  and  thumb -screw,  for  setting  the  instrument  at  any  required 
speed. 


Il8  QUEEN   &   CO.,   INC.,   PHILADELPHIA. 

1135.     Hill's  Railroad  Time  Charts. 

The  principal  features  of  the  charts  are  : 

1.  The  positively  mathematical  correctness  of  the  spacing. 

2.  The  ease  with  which  the  five  minutes,  half  hour,  and  hour  lines 
can  be  distinguished,  as  well  as  their  perfect  clearness  and  cleanness. 

3.  Their  enormous  size  (28x50),  admitting  of  larger  hour-spaces  than 
any  chart  at  present  in  use. 

4.  The  excellence  of  the  paper  on  which  they  are  printed,  as  well  as  its 
peculiar  tint,  rendering  it  peculiarly  fit  for  night  work,  while  its  cardboard- 
like  texture  obviates  the  necessity  for  dampening  and  stretching,  and  the 
consequent  distortion  of  the  diagram. 

5.  Their  cheapness,  which  enables  us  to  furnish  them  to  railroads  in 
smaller  quantities  and  at  lower  price  than  they  could  be  obtained  by  litho- 
graphic or  any  other  process. 

The  "  Speed  Protractor,"  which  is  generally  used  with  the  charts, 
needs  hardly  any  recommendation.  The  simplicity  of  its  construction,  the 
care  bestowed  in  its  manufacture,  its  greater  accuracy  than  that  of  the  semi- 
circular angle  protractor,  and  its  low  price,  speak  for  themselves. 

The  price  of  the  Charts,  without  name  of  stations,  station  lines,  and 
heading,  is  $12.00  per  quire;  complete  and  ready  for  train  plotting,  the 
scale  of  prices  is  as  follows,  viz.: 

50  Sheets ,.;.,...    .   .  $75  oo 

100      do no  oo 

150     do 1 20  oo 

200     do 1 60  oo 

Speed  Protractor 10  oo 

In  favoring  us  with  an  order  for  complete  charts,  please  send  list  of 
stations  with  intermediate  distances,  and  underscore  such  stations  as  you  may 
desire  to  have  printed  in  heavy  type  on  account  of  their  importance. 

The  following  is  an  extract  from  a  letter  of  Mr.  James  Tillinghast, 
General  Superintendent  of  the  New  York  Central  and  Hudson  River  Rail- 
road,  to  whose  judgment  Mr.  Hill  submitted  both  charts  and  protractor: 

NEW  YORK  CENTRAL  AND  HUDSON  RIVER  RAILROAD,  1 
Gen'l  Supt  Office,  Albany,  N.  Y.,  Jan.  I5th,  1876.  ] 
"ALBERT  HILL,  ESQ.: 

"  Dear  Sir : — I  am  in  receipt  of  yours  of  the  I4th  inst.,  with  sample  of  diagram  of 
Chart  sheets.  *  *  *  I  have  not  found  any  better  plan  to  secure  accuracy  in  forming 
the  basis  or  proof  of  time  tables,  for  the  reason  that  it  presents  to  the  eye  in  a  clear,  con- 
densed form,  all  the  trains  the  schedule  is  to  cover,  and  in  such  manner  that  the  station 
figures  are  accurately  indicated,  and  from  which  the  figures  for  .the  printed  form  can  be 
readily  copied. 

"  Your  plan  of '  Speed  Protractor  '  is  the  best  I  have  seen,  and  will  be  tery  useful 
in  connection  with  the  Charts,  and  I  have  no  doubt  that,  with  the  facilities  you  mention 
for  the  production  of  charts  so  accurately  lined  as  your  process  will  produce,  you  will  be 
able  to  .secure  orders.  *  *  *  Yours  truly, 

"JAMES  TILLINGHAST." 

The  following  is  a  list  of  some  of  the  principal  railroad  companies  by 
which  these  Charts  have  been  so  far  adopted  : 
Pennsylvania  Railroad. 
Central  Railroad  of  New  Jersey. 
Lake  Shore  and  Michigan  Southern  Railroad. 
Toledo,  Wabash  and  Western  Railway. 
Cleveland,  Tuscarawas  and  Wheeling  Railroad,  etc.,  etc. 
If  desired,  we  will  send  by  mail,  postage  paid,  a  chart  of  any  of  the 
above-named  roads,  as  a  sample. 


QUKEN  &  CO.,   INC.,   PHILADELPHIA. 

Architecture,  Carpentry  and  Building. 


Bell.— Carpentry  Made  Easy.— Or, 
the  Science  and  Art  of  Framing  on  a 
New  and  Improved  System.  With 
Specific  Instructions  for  Building  Bal- 
loon Frames,  Barn  Frames,  Mill 
Frames,  Warehouses,  Church  Spires, 
etc.  Comprising  also  a  System  of 
Bridge  Building,  with  Bills,  Estimates 
of  Cost,  and  Valuable  Tables.  Illus- 
trated by  fprty-four  plates,  comprising 
nearly  200  figures.  Svo.  $5.00. 

Birkmire. — Architectural  Iron  and 
Steel,  and  its  Application  in  the  Con- 
struction of  Buildings.  Fully  illustra- 
ted from  original  designs.  8vo.  $3.00 

Birkmire. — Skeleton  Construction 
in  Buildings.  Fully  illustrated  with 
engravings  from  Practical  Examples 
of  High  Buildings.  Svo.  $3.00 

Birkmire.  —  Compound  Riveted 
Girders  as  applied  in  Buildings.  Svo. 
$2.00 

Brooks. — Rudimentary  Treatise  on 
the  Erection  of  Dwelling  Houses.  111., 
I2mo.,  boards.  London.  $1.00 

Brunner. — Cottages,  or  Hints  on 
Economical  Building,  containing  24 
plates  of  Medium  and  Low  Cost 
Houses,  and  a  Chapter  on  the  Water 
Supply,  Drainage,  Sewerage,  Heating 
and  Ventilation,  etc.  Svo.  N.Y.  $1.00. 

Bryan. —  Architectural  Proportion. 
A  new  system  of  proportion  showing 
the  relation  between  an  order  of  archi- 
tecture and  a  building  of  any  kind. 
4to.  San  Francisco.  $1.50. 

Bullock. — The  American  Cottage 
Builder. — A  .Series  of  Designs,  Plans 
and  Specifications,  from  $200  to  $20,- 
ooo,  for  Homes  for  the  People;  to- 
gether with  Warming,  Ventilation, 
Draining,  Painting  and  Landscape 
Gardening.  By  John  Bullock,  Archi- 
tect, Civil  Engineer,  Mechanician. 
Illustrated  by  75  engravings.  326  pp. , 
Svo.  $3.00. 

Bullock. — The  Rudiments  of  Archi- 
tecture and  Building. — For  the  use  of 
Architects,  BuiJders,  Draughtsmen, 
Machinists,  Engineers  and  Mechanics. 
Edited  by  John  Bullock.  Illustrated 
by  250  Engravings.  468  pp.  Svo. 
$3.00. 

Bury. — Architecture.  The  Styles  of 
Architecture  of  Various  Countries 


from  the  earliest  to  the  present  period, 
111.,  I2mo.  boards.     London.     So  cts. 

Clark. — Building  Superintendence. 
A  Manual  for  young  Architects,  Stu- 
dents and  others  interested  in  Build- 
ing Operations  as  carried  on  at  the 
present  day.  111.,  I2mo.  $3.00. 

Collins. — A  Practical  Treatise  on 
Handrailing.  111.,  I2mo.  boards,, 
London.  60  cts. 

Creswell. — Handrailing  and  Stair- 
casing  ;  a  Complete  Set  of  Lines  for 
Handrails  by  "Square  Cut  "System, 
and  full  Practical  Instructions  for 
Making  and  Fixing  Geometrical  Stair- 
cases. 100  Working  Drawings.  I2mo. 
London.  $1.50. 

Davis — A  Practical  Treatise  on  the 
Manufacture  of  Bricks,  Tiles,  Terra- 
Cotta,  etc.;  including  Hand-made, 
Dry  Clay,  Tempered  Clay,  Soft  Mud, 
and  Stiff  Clay  Bricks,  also  Front, 
Hand-Pressed,  Steam-Pressed,  Re- 
Pressed,  Ornamentally  Shaped  and 
Enanimelled  Bricks,  Drain  Tiles, 
Straight  and  Curved  Sewer  and  Water- 
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Merrett. — A  Practical  Treatise  on 
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Bauerman.  —  Text-Book  of  Sys- 
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Bauerman.  —  A  Treatise  on  the 
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Beard. — The  Ventilation  of  Mines. 
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Blair. — The  Chemical  Analysis  of 
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Bloxam. — Metals,  their  Properties 
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£olton.—The  Students'  Guide  in 
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Booth  and  Morfit. — The  Encyclo- 
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Bowie.  —  A  Practical  Treatise  on 
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description  of  the  Use  and  Construc- 
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Brough. — A  Treatise  on  Mine  Sur- 
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Brown. — Manual  of  Assaying  Gold, 
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Brush. — Manual  of  Determinative 
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Chester. — A  Catalogue  of  Minerals, 
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Classen.  —  Quantitative  Chemical 
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Dana. — Text-Book  of  Geology. 
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Dana.  —  The  Geological  Story, 
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Dana. — Manual  of  Mineralogy  and 
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De  Koninck  and  Dielz. — A  Practical 
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Egleston. — Catalogue  of  Minerals. 
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Eissler. — Cyanide  Process  for  the 
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Erni. — Mineralogy  Simplified.  Easy 
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Fleischer. — A  System  of  Volumetric 
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Fletcher. — Practical  Instructions  in 
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Foster.— A  Text-Book  of  Ore  and 
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Frazer. — Tables  for  the  Determina- 
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Furman. — A  Manual  of  Practical 
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Geikie. — Outlines  of  Field  Geology. 
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Geikie.  —  Text-Book  of  Geology. 
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Gore. — The  Art  of  Electrolytic  Sep- 
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Greenwood. — Steel  and  Iron,  Com- 
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Guttmann. — Blasting.  A  Hand- 
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Hussak. — The  Determination  of 
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Jannettez. — A  Guide  to  the  Deter- 
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Second  Edition,  revised.  Illustrated. 
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Kemp. — The  Ore  Deposits  of  the 
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Kerl. — The  Assayers'  Manual.  An 
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KerL—  Practical  Treatise  on  Metal- 
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Lieber. — The  Assayers'  Guide;  or> 
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Lintern. — The  Mineral  Surveyor 
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Lock. — Practical  Gold  Mining.  A 
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Lock. — Mining  and  Ore-Dressing 
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Lupton. — Mining.  An  Elementary 
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Lyell. — Principles  of  Geology  ;  or, 
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Makins. — A  Manu&l  of  Metallurgy, 
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Mitchell. — A  Manual  of  Practical 
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Moses  and  Parsons. — Elements  of 
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Mott.—The  Chemists'  Manual.  A 
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O'Driscoll. — Notes  on  the  Treat- 
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Orton.  —  Underground  Treasures, 
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Percy.— Metallurgy .  The  Art  of  Ex- 
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Percy.— Silver  and  Gold.  Part  I. 
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Rose.—  The  Metallurgy  of  Gold. 
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Ross.— The  Blowpipe  in  Chemistry. 
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1  us  i  rated. 

XIII.  A  PRACTICAL  TREATISE  ON  THE  GASES  MET  WITH  IN  COAL  MINES.    By 
the  late  J.  J.  Atkinson,  Government  Inspector  of  Mines  for  the  County  oi 
Durham,  England. 

XIV.  FRICTION  OF  AIR  IN  MINES.     By  J.  J.  Atkinson,  author  of  "A  Practical 
Treatise  on  the  Gases  Met  With  in  Coal  Mines." 

XV.  SKEW  ARCHES.     By  Prof.  E.  W.  Hyde,  C.E      Illustrated  with  numerous  en 
graving'^  and  three  folded  plates. 

XVL  A  GRAPHIC  METHOD  FOR  SOLVING  CERTAIN  ALGEBRAIC  EQUATIONS.  Bj 
Prof.  George  L.  Vose.  With  illustrations. 

XVIL  WATER  ANI  WATER  SUPPLY.  By  Prof.  W.  H.  Corfield,  M.  A.,  of  the  Uni- 
versity Co^ege,  London. 

XVIII  SEWERAGE  AND  SEWAGE  UTILIZATION.  By  Prof.  W.  H.  Corfield,  M.  A« 
of  the  University  College,  London 


QUEEN   &  CO.,   INC.,   PHILADELPHIA. 

JCIX.  STRENGTH  OF  BEAMS  UNDER  TRANSVERSE  LOADS.     By   ProL  W. 
author  of  "  Theory  of  Arches."     With  illustrations. 

XX.  BRIDGE  AND  TUNNEL  CENTRES.    By  John  B.  McMasters,  0.  E.    With  ilia* 
trations. 

XXI.  SAFETY  VALVES.    By  Richard  H.  Buel,  C.  E.    With  illustrations. 

XXII.  HIGH  MASONRY  DAMS.    By  John  B.  McMasters,  C.E.      With  illustrations. 

XXIII.  THE  FATIGUE  OF  METALS  under  Repeated  Strains,  with  various  Tables  of 
Results  and  Experiments.    From  the  German  of  Prof.  Ludwig  Spangenberg. 
WTith  a  Preface  by  S.  H.  Shreve,  A.  M.     With  illustrations. 

XXIV.  A  PRACTICAL  TREATISE  ON  THE  TEETH  OF  WHEELS,  with  the  theory  4! 
the  use  of  Robinson's  Odontograph.     By  S.  W.  Robinson,  Prof,  of  Mechanical 
Engineering,  Illinois  Industrial  University. 

XXV.  THEORY  AND  CALCULATIONS  OF  CONTINUOUS  BRIDGES.    By  Mansfield  Mer 
riman,  C.  E.     With  illustrations. 

XXVI.  PRACTICAL  TREATISE  ON  THE  PROPERTIES  OF  CONTINUOUS  BRIDGES.    By 
Charles  Bender,  C.  E. 

XXVII.  ON  BOILER  INCRUSTATION  AND  CORROSION.     By  F.  J.  Rowan.     With 
illustrations. 

XXVIII.  ON  TPVNSMISSION  OF  POWER  BY  WIRE  ROPE.    By  Albert  W.  Stahl. 
With  illustrations. 

XXIX.  INJECTORS.    The  Theory  and  Use.    Translated  from  the  French  af  M.  Leon 
Pochct.     With  illustrations. 

XXX.  TERRESTRIAL  MAGNETISM  AND  THE  MAGNETISM  OF  IRON  SHIPS.    By  Prof 
Fairn:an  Rogers.     With  illustrations. 

XXXI.  THE  SAriTARY  CONDITION  OF  DWELLING  HOUSES  IN  TOWN  AND  COUNTRY. 
Bv  George  Fs  Waring,  Jr.     With  illustrations. 

XXXII.  CABLE  MAKING  OF  SUSPENSION  BRIDGES  AS  EXEMPLIFED  IN  THE  EASI 
RIVER  BRI»KJE.     By  WTilhelm  Hildenbrand,  C.  R    With  illustrations. 

XXXIII.  MECHANICS  OF  VENTILATION.    By  George  W.  Rafter,  Civil  Engineer. 

XXXIV.  FOUNDATIONS.      By  Prof.  Jules  Gaudard,  C.E.      Translated   from   the 
French  by  L.  F.  Vernon  Harcourt,  M.  I.  C.  E. 

XXXV.  THE  ANEROID  BAROMETER,  ITS  CONSTRUCTION  AND  USE.     Compiled  bj 
Prof.  Geo.-ge  W.  Plympton.     Illustrated. 

XXXVI.  MATTER  AND  MOTION.    By  J.  Clerk  Maxwell,  M.  A. 

XXXVII.  GEOGRAPHICAL   SURVEYING.    Its  Uses,  Methods,  and  Results.     Bj 
Frank  L»e  Yeaux  Carpenter,  C.  E. 

XXXVI II.  MAXIMUM  STRESSES  IN  FRAMED  BRIDGES.    By  Prof.  Wm.  Cain,  A.  Mn 
C.E.     Illustrated. 

XXXIX.  A  HAND-BOOK  OF  THE  ELECTRO-MAGNETIC  TELEGRAPH.      By  A.  £, 
Loring.     Illustrated. 

XL.  TRANSMISSION  OF  POWER  BY  COMPRESSED  AIR.  By  Robert  7*hner,  M.  fi 
Illustrated. 

XLI.  ON  THE  STRENGTH  OF  MATERIALS.    By  Wm.  Kent,  C.  E. 

XLII.  VOUSSOIR  ARCHES  APPLIED  TO  STONE  BRIDGES,  TUNNELS,  ETC.  By  Prof 
W.  Cain. 

XLIII.  WAVE  AND  VORTEY  MOTION.  B$  Thomas  Craig,  Ph.D.,  Johns  Hopkini 
University,  Baltimore. 

XLIV.  TURBINE  WHEELS  :  on  the  Inapplicability  of  the  Theoretical  Investiga- 
tions of  the  Turbine  Wheel,  as  given  by  Rsmkine  and  others  to  the  modern 
constructions.  By  Prof.  W.  P.  Trowbridge,  Columbia  College. 

XLV.  THERMODYNAMICS.  By  Ilenr^  T.  Eddy,  C.  E.,  Ph.  D.,  University  of  Cincin 
nati.  Illustrated. 

4LVI.  ICE-MAKING  MACHINES.    The  Theory  of  the  A  ct^on  of  the  various  Fvnx* 
of  so-called  Ice  Machines.    Translated  from  the  French  of  M.  Ledoux. 
Crated. 


QUEEN   &   CO.,   INC.,   PHILADELPHIA. 

XL VII.  LINKAGES:  the  different  Forms  and  Uses  of  Articulated  Links.     By  J,  D. 

C.  DeRoos.     From  the  French.     Illustrated. 
XLVIII.  THEORY  OP  SOLID  AND  BRACED  ARCHES:  applied  to  Arch  Bridges  and 

Roofs  in  Iron,  Wood,  Concrete,  or  other  material.     By  William  Cain,  C.  E, 
XLIX.  ON  THE  MOTION  OP  A  SOLID  IN  A  FLUID,  AND  THE  VIBRATIONS  OF  LIQUID 

SPHEROIDS      By  Thomas  Craig,  Ph.  D.     Illustrated. 
L.  DWELLING  HOUSES:  their  Sanitary  Construction  and  Arrangements.     Bvr  Prof 

WT.  H.  Cortield,  M.  A  ,  M.D. 
LI.  THE  TELESCOPE:   the  Principles  involved  in  the  Construction  of  Refracting  and 

Reflecting  Telescopes.     By  Thomas  Nolan,  B. S.     With  illustrations. 
LII.  IMAGINARY  QUANTITIES:  their  Geometrical  Interpretation.     Translated  from 

the  French  of  M.  Argand.     By  Prof.  A.  S.  Hardy.     * 
LIII.  INDUCTION  COILS:  how  Made  and  how  Used.     Illustrated. 
LIV.  THE  KINEMATICS  OP  MACHINERY  ;  or,  the  Elements  of  Mechanism.     By 

Prof.  A.  B.  W.  Kennedy.     With  a  Preface  by  Prof.  R.  H.  Thurston, 
I-V    SEWER  GASES  :  their  Nature  and  Origin,  and  how  to  Protect  oui  Dwellings. 

By  Adolfo  de  Varona,  A.  M.,  M.  D.     With  illustrations. 
LVI.  THE  ACTUAL  LATERAL  PRESSURE  OF  EARTHWORK.    By  Benjamin  Baker, 

M.  Inst.  C.  E. 
LVIT.  INCANDESCENT  ELECTRIC  LIGHTS,  WITH  PARTICULAR  REFERENCE  TO  THE 

EDISON  LAMPS  AT  THE  PARIS  EXHIBITION.  By  Comte  Th.  du  Moncel,  William 

Henry  Preece,  J.  W.  Howell,  and  others.     Third  edition,  in  press. 
LVI  1 1.  THE  VENTILATION  OF  COAL-MINES.    By  W.  Fairley,  M.  E.,  F.  S.  S. 
LIX.  RAILROAD    ECONOMICS;  or,  Notes,  with    Comments.     By  S.  W.  Robinsonr 

C.  E. 

LX.  STRENGTH  OF  WROUGHT-!RON  BRIDGE  MEMBERS.    By  S.  W.  Robinson,  C.  E, 
LXI.  POTABLE  WATER  AND  THE  DIFFERENT  METHODS  OF  DETECTING  IMPURITIES, 

By  Charles  W.  Folkard. 

LXII.  THE  THEORY  OF  THE  GAS-ENGINE.     By  Dugald  Clerk. 
LXIil.  HOUSE  DRAINAGE  AND  SANITARY  PLUMBING.    By  W.  P.  Gerhard. 
LXIV.  ELECTRO-MAGNETS.     By  Th.  du  Moncel.     Second  revised  edition. 
LXV.  POCKET  LOGARITHMS  TO  FOUR  PLACES  OF  DECIMALS. 
LXVI.  DYNAMO-ELECTRIC  MACHINERY.    By  S.  P.  Thompson.     With  notes  by  F. 

L.  Pope.     Third  edition. 

LXV  1 1.  HYDRAULIC  TABLES  BASED  ON  "  KUTTER'S  FORMULA."     By  P.  J.  Flynn. 
LXVIII.  STEAM-HEATING.    By  Robert  Briggs.    Second  edition,  icvised,  with  ad- 
ditions by  A.  R.  Wolff. 
LXIX.  CHEMICAL  PROBLEMS.    By  Prof.  J.  C.  Foye.    Second  edition,  revised  and 

enlarged. 

LXX.  EXPLOSIVES  AND  EXPLOSIVE  COMPOUNDS.    By  M.  Bertholet. 
LXXI.  DYNAMIC  ELECTRICITY.  By  John  Hopkinson,  J.  A.  Schoolbred,  and  R.  E, 

Day. 
LXXII.  TOPOGRAPHICAL  SURVEYING.      By  George  J.  Specht,  Prof.  A.  S.  ^lardy, 

John  B.  Me  Master,  and  H.  F.  Walling. 
LXXIII.  SYMBOLIC    ALGEBRA;    or,  The    Algebra    of    Algebraic  Numbers-     By 

Prof.  W.  Cain. 
LXXIV.  TESTING    MACHINES:     Their    History,    Construction,    and     Use.      By 

Arthur  V.  Abbott. 
LXXV.  RECENT  PROGRESS  IN  DYNAMO-ELECTRIC  MACHINES.  Being  a  Supplement 

to  Dynamo-Electric  Machinery.     By  Prof.  Sylvanus  P.  Thompson. 
LXXVI.   MODERN   REPRODUCTIVE  GRAPHIC   PROCESSES.     By  Lieut.  James  S. 

Pettit.  U.  S.  A. 


QEEEN  &   CO.,  INC.,  PHILADELPHIA. 

LXXVII.  STADIA  SURVEYING.  The  Theory  of  Stadia  Measurements.  By  Ar- 
thur Winsio-s-. 

LXXVIII.  THE  STEAM-ENGINE  INDICATOR,  AND  ITS  USE.    By  W.  B.  Le  Van. 

LXXIX.  THE  FIGURE  OF  THE  EARTH.     By  Frank  C.  Roberts,  C.  E. 

LXXX.  HEALTHY  FOUNDATIONS  FOR  HOUSES.     By  Glenn  Brown. 

LXXXI.  WATER  METERS.  Comparative  Tests  of  Accuracy,  Delivery,  Etc. 
Distinctive  Features  of  the  Worthington,  Kennedy,  Siemens  and  Hesse 
meters.  By  Ross  F.  Browne. 

LXXXII.  THE  PRESERVATION  OF  TIMBER  BY  THE  USE  OF  ANTISEPTICS.    By 

Samuel  Bagster  Boulton,  C.  E. 

LXXXIII.  MECHANICAL  INTEGRATORS.     By  Prof.  Henry  S.  H.  Shaw,  C.  E. 
LXXXIV.  FLOW  OF  WATER  IN  OPEN  CHANNELS,  PIPES,  CONDUITS,  SEWERS, 

ETC.    With  Tables.     By  P.  J.  Flynn,  C.  E. 
LXXXV.  LUMINIFEROUS  ^THER.     By  Prof,  de  Volson  Wood. 

LXXXVI.  HAND-BOOK  OF  MINERALOGY  ;  Determination  and  Description  of 
Minerals  Found  in  the  United  States.  By  Prof.  J.  C.  Foye. 

LXXXVII.  TREATISE  ON  THE  THEORY  OF  THE  CONSTRUCTION  OF  HELICOIDAI, 
OBLIQUE  ARCHES.  By  John  L.  Culley,  C.  E. 

LXXXVIII.  BEAMS  AND  GIRDERS.  Practical  Formulae  for  their  Resistance. 
By  P.  H.  Philbrick. 

LXXXIX.  MODERN  GUN-COTTON  ;  Its  Manufacture,  Properties  and  Analysis. 
By  Lieut.  John  P.  Wisser,  U.  S.  A. 

XC.  ROTARY  MOTION,  AS  APPLIED  TO  THE  GYROSCOPE.  By  Gen.  J.  G.  Bar- 
nard. 

XCI.  LEVELING.  Barometric,  Trigonometric,  and  Spirit.  By  Prof.  I.  O. 
Baker. 

XCII.  PETROLEUM  :  Its  Production  and  Use.  By  Boverton  Redwood,  F.  I.  C., 
F.  C.  S. 

XCII  I.  NOTES  EMBODYING  THE  RECENT  PRACTICE  IN  THE  SANITARY  DRAIN- 
AGE OF  BUILDINGS.  With  Memoranda  on  the  Cost  of  Plumbing  Work.  By 
William  Paul  Gerhard,  C.  E. 

XCIV.  THE  TREATMENT  OF  SEWAGE.     By  Dr.  C.  Meymott  Tidy. 

XCV.  PLATE  GIRDER  CONSTRUCTION.     By  Isami  Hiroi,  C.  E. 

XCVI.  ALTERNATE  CURRENT  MACHINERY.  By  Gisdert  Kapp,  Assoc.  M.  Inst., 
C.  E. 

XCVII.  THE  DISPOSAL  OF  HOUSEHOLD  WASTE.  By  W.  Paul  Gerhard,  Sanitary 
Engineer. 

XCVIII.  PRACTICAL  DYNAMO-BUILDING  FOR  AMATEURS.  How  To  WIND  FOR 
ANY  OUTPUT.  By  Frederick  Walker.  Fully  Illustrated. 

XCIX.  TRIPPLE-EXPANSION  ENGINES  AND  ENGINE  TRIALS.  By  Prof.  Osborne 
Reynolds.  Edited  with  notes,  etc.,  by  F.  E.  Idell,  M.  E. 

C.  How  To  BECOME  AN  ENGINEER,  or  the  Theoretical  and  Practical  Training 
necessary  in  fitting  for  the  duties  of  the  Civil  Engineer.  By  Prof.  Geo.  W. 
Plympton. 

CI.  THE  SEXTANT,  and  other  Reflecting  Mathematical  Instruments.  With 
Practical  Hints  for  their  adjustment  and  use.  By  F.  R.  Brainard,  U.  S. 
Navy. 

CII.  THE  GALVANIC  CIRCUIT  INVESTIGATED  MATHEMATICALLY.  By.  Dr.  G. 
S.  Oem,  Berlin,  1827.  Translated  by  William  Francis.  With  Preface  and 
Notes  by  the  Editor,  Thomas  D.  Lockwood.  M.  I.  E.  E. 

CHI.  THE  MICROSCOPICAL  EXAMINATION  OF  PORTABLE  WATER.  With  Dia- 
grams. By  Geo.  W.  Rafter. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA. 

CIV.  VAN  NOSTRAND'S  TABLE  BOOK  FOR  CIVIL  AND  MECHANICAL,  ENGINEERS. 

Compiled  by  Prof.  Geo.  W.  Plympton. 
CV.  DETERMINANTS.    An  Introduction  to  the  Study  of,  with  Examples  and 

Applications.     By  Prof.  G.  A.  Miller. 
CVI.  COMPRESSED  AIR.     Experiments  upon  the  Transmission  of  Power  by 

Compressed  Air  in  Paris.     (Popp's  System.)     By  Prof.  A.  B.  W.  Kennedy. 

The  Transmission  and  Distribution  of  Power  from  Central  Stations  by  Com- 
pressed Air.     By  Prof.  W.  C.  Unwin. 
CVII.  A  GRAPHICAL  METHOD  FOR  SWING-BRIDGES.    A  Rational  and  Easy 

Graphical  Analysis  of  the  Stresses  in  Ordinary  Swing-Bridges.     With  an 

Introduction  on  the  General  Theory  of  Graphical  Statics.     By  Benjamin  F. 

La  Rue.     4  Plates. 
CVIH.  SLIDE  VALVE  DIAGRAMS.    A  French  Method  of  Obtaining  Slide  Valve 

Diagrams.     By  Lloyd  Bankson,  B.  S.,  Assistant  Naval  Constructor,  U.  S. 

Navy.     8  Folding  Plates. 
riX.  THE  MEASUREMENT    OF  ELECTRIC  CURRENTS.    Electrical    Measuring 

Instruments.     By  James  Swinburne.     Meters  for  Electrical  Energy.     By 

C.  H.  Wordingham.    Edited,  with  Preface,  by  T.   Cornmerford  Martin. 

Folding  Plate  and  numerous  illustrations. 


QUEEN  &   CO.,   INC.,   PHILADELPHIA.  143 


ENGINEERS  AND 
SURVEYORS  SAY 

...OF  OUR... 

ENGINEERING    INSTRUMENTS. 


(Copy.) 

GIRARD,  O.,  March  ist,   1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

About  the  ist  of  February,  1895,  we  purchased  from  you  one 
Full  Engineers'  Transit,  No.  A 1494,  and  one  Engineers'  Level,  No. 
A  1528,  which  we  have  had  in  use  at  our  mine  in  Minnesota  ever 
since,  and  we  are  ready  to  say  that  we  have  had  the  very  best 
results,  and  they  are  pronounced  by  civil  engineers  to  be  standard 
instruments,  and  were  we  in  need  again  of  the  same  kind  of 
instruments  we  would  order  them  exactly  like  the  ones  you  sent  us. 

Yours  truly, 

BIWABIK  BESSEMER  COMPANY, 
(Signed)  HENRY  B.  SHIELDS, 

Secretary. 


(Copy.) 

NEW  ORLEANS,  LA.,  March  6th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

We  are  in  receipt  of  yours  of  the  3d  inst.  in  regard  to  the 
Reconnoissance  Transit,  No.  A  1518,  purchased  from  your  company 
by  our  firm  July  23d,  1895.  In  reply  we  would  say  that  this  instru- 
ment has  given  very  good  satisfaction. 

Yours  very  truly, 
(Signed)  FORD,  BACON  &  DAVIS. 


^44  QUEEN  &  CO.,   INC.,   PHILADELPHIA. 

(Copy.) 

EBENSBURG,  PA.,  March  5th,   1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS:— 

The  Full  Engineers'  Transit,  No.  A 1494,  purchased  from  you  in 
1895  has  given  the  most  perfect  satisfaction.  I  can  truthfully  say 
that  without  exception  the  graduations  are  the  most  accurate  that  I 
have  ever  seen,  and  the  optical  quality  of  the  telescope  without  an 
equal.  It  is  the  only  instrument  I  have  been  able  to  work  with  the 
entire  day  without  the  nerves  of  my  eyes  being  greatly  strained  and 
tired.  The  power,  being  exceedingly  high,  does  not  reduce  the 
amount  of  light  or  field  in  the  least. 

Yours  truly, 
(Signed)  C.  T.  ROBERTS. 


(Copy,) 

COLUMBIA,  PA.,  March  i5th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

The  Reconnoissance  Transit,  No.  A  1518,  that  I  purchased  from 
you  in  1894  has  proven  itself  to  be  of  very  accurate  construction  and 
has  served  my  purpose  very  satisfactorily..  I  consider  it  equally  as 
good  as  any  builders'  transit  on  the  market,  and  am  very  much 
pleased  to  be  in  possession  of  so  fine  an  instrument. 
Yours  very  respectfully, 

(Signed)  JEREMIAH  KOCH, 

Architect. 

(Copy.) 

LYLES,  PA.,  March  3d,   1897. 
QUEEN  &  Co.,  INC., 
GENTLEMEN  : —  ^ 

The  Surveyors'  Transit,  No.  A 1502,  purchased  from  you  in 
November,  1894,  has  been  very  satisfactory  to  me,  and  my  work 
with  it  has  always  been  received  by  my  customers  with  apparently 
entire  satisfaction. 

Yours  truly, 
(Signed)  ALFRED  WOOD, 

Surveyor. 


QUEEN   &   CO.,   INC.,   PHILADELPHIA.  145- 

(Copy.) 

RUNGE,  TEXAS,  April  22d,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN : — 

Your  favor  of  the  24th  inst.  came  duly  to  hand",  and  through 
momentarily  setting  it  aside  for  more  pressing  matter,  it  was  over- 
looked. Apologizing  for  the  neglect,  I  hasten  to  state  that  I  have 
had  the  Surveyors'  Transit,  No.  A 1502,  purchased  from  you  in  use 
for  a  year  now.  In  that  time  I  have  laid  off  one  town  site,  Nord- 
heim,  on  the  line  of  the  San  Antonio  and  Arkansas  Pass  Railway, 
and  done  a  multiplicity  of  other  work,  in  all  of  which  I  have  been 
pleased  with  my  instrument  to  an  eminent  degree.  It  has  come 
fully  up  to  my  expectations. 

Yours  truly, 
(Signed)  WM.  H.  LECKIE, 

Eight  years  County  Surveyor, 

Kansas  County,  Texas. 


(Copy.) 

Laurens  Cotton  Mills. 

LAURENS,  S.  C.,  March  6th,  1897. 
MES'SRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

We  are  pleased  to  say  that  the  Full  Surveyors'  Transit,   No.. 
A  1502,  purchased  of  you  is  entirely  satisfactory. 

Yours  truly, 
(Signed)  W.  E.  LUCAS, 

President  and  Treasurer. 


(Copy.) 

TAMAQUA,  PA.,  March  4,  1897. 
MESSRS.  J^UEEN  &  Co.,  INC., 
DEAR  SIRS  :— 

Your  Surveyors'  Transit,  No.  A 1502,,   has  been  received  and 
we  find  it  first-class  in  every  particular. 

Yours  respectfully, 
(Signed)  WEAVER,  SON  &  HALDEMAN, 

Builders  and  Contractors. 


146  QUEEN  &  CO.,   INC.,   PHILADELPHIA. 

(Copy.) 
Buffalo,  Rochester  and  Pittsburg  Railway  Company. 

ROCHESTER,  N.  Y.,  March  4th,  1897. 
QUEEN  &  Co.,  INC., 
GENTLEMEN :— 

The  Reconnoissance  Transit,  No.  A  1508,  which  I  purchased  oi 
you  for  the  use  of  one  of  my  relatives  has  given  entire  satisfaction. 
It  seems  .to  have  been  very  well  and  thoroughly  made,  and  the 
graduations  are  very  accurate. 

Yours  very  truly, 
(Signed)  WM.  E.  HOYT, 

Chief  Engineer  B.,  R.  &  P.  Rwy. 


(Copy.) 
254.1  Third  Avenue.  NEW  YORK,  February  22d,  1897 

MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

I  have  been  constantly  using  the  Engineers'  Transit,  No. 
A  1494,  which  I  bought  from  you  in  1895,  and  I  can  safely  say,  not- 
withstanding the  very  inclement  weather  it  has  been  subjected  to, 
it  has  proved  entirely  satisfactory  and  one  of  the  best  instruments  I 
have  used  ;  my  experience  having  covered  a  period  of  twenty  years 

Respectfully  yours, 
(Signed)  P.  E.  AMIOT,  B.  S.  A., 

Civil  Engineer  and  City  Surveyor. 


(Copy.) 

Department  of  Public  Works, 
Fifth  Survey  District, 

521  West  Venango  St. 

PHILADELPHIA,  June  gth,  189^ 
QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

The  City  and  Bridge  Transit,  A  1490,  which  you  built  for  me 
about  three  years  ago  has  given  perfect  satisfaction. 

Yours  truly, 
(Signed)  WALTER  BRINTON, 

Sur.  and  Reg.  Fifth  Dist. 


QUEEN   &   CO.,    INC.,    PHILADELPHIA.  147 

(Copy.) 

RosELLE,  N.  J.,  April  6th,   1897. 
QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

Referring  to  your  Engineers'  Transit,  No.  A 1494,  will  say  that 
I  have  been  much  pleased  with  the  work  I  have  been  able  to  do 
with  the  instrument.  It  has  been  tested  where  varying  degrees  of 
accuracy  were  required,  and  the  results  have  always  been  satis- 
factory. 

I  should  be  pleased  to  recommend  it  to  any  would-be  pur- 
chasers. 

Yours  truly, 
(Signed)  J.  WALLACE  HIGGINS. 


(Copy.) 
Wellington  &  Powdlsville  R.  R.   Co. 

EDENTON,  N.  C.,  March  8th,   1897. 
MESSRS.  QUEEN  &  Co., 
DEAR  SIRS: — 

Replying  to  your  favor  of  the  2d,  would  say  that  the  Engineers* 
Transit,  No.  A 1494,  we  bought  of  you  in  1895  our  chief  engineer 
says  is  one  of  the  finest  he  ever  used.  We  notice  since  he  has  had 
this  instrument  that  he  has  been  able  to  give  us  better  curves  and 
grades  over  our  road  than  he  formerly  did  with  the  old  instrument. 
Therefore  we  think  it  far  superior  to  anything  that  we  have  had. 

Yours  truly, 
(Signed)  J.  W.  BRANNING, 

President. 

(Copy.) 

DUSHORE,  PA.J  February,  4th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

The  Surveyors'  Transit,  No.  A 1502,  which  I  bought  of  you  in 
May,  1895,  is  an  excellent  instrument  and  has  given  the  best  ot 
satisfaction.  I  do  not  believe  that  it  can  be  surpassed,  and  the 
engineer  owning  one,  is  well  equipped  to  do  accurate  work. 

Respectfully  yours, 
(Signed)  NATHAN  PERSUN,  C.  E. 


148  QUEEN   &   CO.,   INC.,   PHILADELPHIA. 

(Copy.) 

PITTSTON,  PA.,  March  6th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

In  reply  to  yours  of  24th  of  February,  it  gives  us  much 
pleasure  to  be  able  to  truthfully  say,  that  the  Transit  you  shipped 
us  on  the  i3th  of  June,  1895,  is  giving  us  entire  satisfaction  in  every 
way. 

We  have  done  some  very  nice  work  with  it  and  in  all  cases 
have  been  able  to  verify  our  work.  The  instrument  has  never  been 
out  of  adjustment  since  we  had  it. 

Yours  truly, 
(Signed)  C.  R.  PATTERSON  &  SON, 

Architects  and  Civil  Engineers. 


(Copy.) 
The  W.  J.  McCahan  Sugar  Refining  Co. 

PHILADELPHIA,  March  4th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS  : — 

Replying  to  your  inqury  of  the  2nd  inst.,  we  beg  to  advise  that 
the  new  improved  Architects'  Level,  No.  A 1532,  purchased  from 
you  in  August,  1894,  has,  so  far,  given  perfect  satisfaction. 

Yours  very  truly, 
THE  W.  J.  McCAHAN  SUGAR  REFINING  CO., 

(Signed)  JAS.  M.  McCAHAN, 

Manager. 
•» 

(Copy.) 

MOORESTOWN,  N.  J.,  Feb.  24th,   1897. 
MESSRS.  QUEEN  &  Co.,  INC.,-  ^ 

GENTLEMEN  : — 

The  Surveyors'  Transit,  No.  Ai5O2,  I  bought  of  you  April  2d, 
1896,  I  find  to  be  a  very  fine  and  accurate  instrument,   and  surely 
-ought  to  satisfy  any  surveyor. 

Yours  truly, 

(Signed)  URIAH  BORTON, 

Surveyor,  Conveyancer  and  Commissioner  of  Deeds. 


QUEEN  &  CO.,   INC.,   PHILADELPHIA.  149 

(Copy.) 
/ 018  Academy  Street.  PHILADELPHIA,  March,   nth,   1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS  : — 

In  answer  to  your  inqury,  the  Architects'  Level,  No.  A  1532, 
which  I  purchased  from  you  in  October,  1894,  is  very  satisfactory 
indeed.  I  have  used  it  a  great  deal,  not  only  saving  time,  but 
obtaining  more  accurate  results. 

I  take  pleasure  in  recommending  it. 

Yours  respectfully, 
(Signed)  CHARLES  J.  W.  PLATT, 

Carpenter  and  Builder. 


(Copy.) 

W.  H.  Ashwell&  Co. 

DETROIT,  MICH.,  Feb.  26th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

In  reply  to  yours  of  the  24th,  regarding  the  Full  Engineers' 
Transit,  No.  Ai494,  and  Engineers'  Y  Level,  No.  A  1528,  pur- 
chased from  you  in  July,  1894,  I  beg  to  say  that  the  same  have 
been  almost  constantly  in  the  field  since  that  time  and  to-day  are 
.virtually  as  good  as  the  day  they  were  purchased. 

Yours  very  truly, 
(Signed)  WM.  H.  ASH  WELL. 


(Copy.) 

W  ABASH,  IND.,  March  i2th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

In  May  1895,  I  purchased  one  of  your  Full  Surveyors'  Tran- 
sits, No.  1502,  it  has  been  in  constant  use  and  has  given  perfect 
satisfaction.  Your  improvements  and  workmanship  are  excellent, 
it  has  proved  to  be  valuable  and  reliable  in  all  respects. 

Yours  very  truly, 
(Signed)  EDWARD  A.  LOWER, 

County  Surveyor  and  Civil  Engineer. 


150  QUEEN   &   CO..    INC.,    PHILADELPHIA. 

(Copy.) 
in   W.  Third  Street.         JAMESTOWN,  N.  Y.,  March  ist,   1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
SIRS  :— 

I  purchased  one  of  your  Engineers'  Transits,  No.  Ai494,  las« 
Fall  and  have  used  it  in  all  kinds  of  weather  since,  part  of  thp  tirm 
the  mercury  close  to  zero  and  found  it  exactly  as  represented. 

Respectfully, 
(Signed)  C.  B.  V&H&Y.. 


(Copy.) 

GRAHAM,  N.  C.,  Manv  'fi'a,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  :— 

The  Engineers'   Transit,  No.  A 1494,  purchased  f/oni  you  on 
July  25th,  1895,  was  for  a  builder  doing  contract  work  for  us.     The 
instrument  seemed  to  please  him  very  much,  and  so  far  as  we 
observed  his  work  was  very  accurate  with  your  instrument. 
Yours  truly, 

ONEIDA  COTTON  MILLS, 
(Signed)  L.  BANKS  HOLT, 

Proprietor. 

(Copy.) 
874  Broadway.  NEW  YORK,  March  i,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS  :— 

The  Architects'  Level,  No.  A 1532,  which  we  purchased  from 
you  about  a  year  ago,  has  proved  satisfactory  beyond  our  expecta- 
tions. While  we  have  never  used  it  for  a  longer  run  than  about 
half  a  mile,  within  that  distance,  sometimes  over  rough  country, 
the  results  have  checked  out  within  one  or  two  hundredths,  tfce  rod 
being  read  only  to  hundreths. 

In  other  words,  on  all  work  for  which  we  have  used  it,  it  has 
been  as  satisfactory  and  appeared  as  accurate  as  if  we  had  used  our 
regular  Engineer's  Level. 

It  has  been  in  nearly  continuous  use  since  we  purchased  it. 

Very  truly  yours, 
(Signed)  WARING,  CHAPMAN  &  FARQUHAR. 


QUEEN   &  CO.,   INC.,   PHILADELPHIA.  151 

(Copy.) 
233  W.  Third  Street.         WILLIAMSPORT,  PA.,  March  4th,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

Referring  to  your  communication  of  2d  inst.,  we  are  pleased  to 
state  that  the  Full  Engineers'  Transit,  No.  A 1494,  we  purchased  of 
you  Nov.  1 7th,  1894,  has  been  in  constant  use  up  to  date.  It  has 
been  a  profitable  instrument  and  we  appreciate  its  value,  as  a  labor 
saving  and  accurate  instrument. 

Most  respectfully, 
(Signed)  W.  H.  C.  HUFFMAN  &  SONS, 

Architects  and  Builders. 


(Copy.) 

CANTON,  PA.,  March  23d,  1897. 
QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

We  have  been  using  your  Engineers '  Transit,  No.  A 1494,  now 
for  over  eighteen  months  and  have  done  some  very  accurate  and 
satisfactory  work.  It  is  very  light  to  carry,  but  at  the  same  time 
very  rigid  and  accurate.  -We  do  not  hesitate  to  say  that  it  is,  in 
our  estimation,  the  height  of  perfection. 

Respectfully  yours, 
(Signed)  CLARK  &  JEWELL, 

Surveyors. 

(Copy.) 
Office  of  County  Surveyor. 

WAVERLY,  O.,  March  8th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

Permit  us  to  say  that  the  20  in.  Improved  Engineers'  Y  Level 
bought  of  you  has,  after  two  years'  service,  proved  to  be  all  that  is 
claimed  for  it ;  and  I  see  no  reason  why  it  should  not  endure  a  life- 
time. Not  a  single  adjustment  has  been  required  in  the  two  years' 
service  to  which  it  has  been  subjected. 

Respectfully, 
(Signed)  H.  W.  OVERMAN, 

County  Surveyor  and  City  Engineer. 


I52  QUEEN   &  CO.,    INC.,   PHILADELPHIA. 

(Copy.) 

STEUBENVILLE,  O.  Feb.  26th,  1897. 
QUEEN  &  Co.,  INC., 
GENTLEMEN  :  — 

The  Complete  Engineers'  Transit,  No.  A 1494,  which  I  bought 
of  you  May  5th,  1894,  has  been  thoroughly  tried  in  active  service 
ever  since,  and  I  have  found  it  the  most  accurate  and  convenient 
transit  I  ever  used. 

Yours  truly, 
(Signed)  C.  E.  FLANAGAN, 

Civil  Engineer, 

(Copy.) 
211  South  roth  Street.  PHILADELPHIA,  Feb.  i9th,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS  : — 

The  Engineers'  Transit,  No.  A 1494,  purchased  from  you  last 
March,  has  given  perfect  satisfaction.  The  operator  is  very  much 
pleased  with  it.  Two  of  our  surveyors  who  furnish  their  own 
instruments  also  use  those  made  by  you  and  speak  very  highly  of 
them. 

Yours  truly, 
(Signed)  D.  L.  RISLEY, 

Real  Estate  Operator. 

.    (Copy.) 
<?7  Church  Street.  NEW  HAVEN,  CONN.,  Feb.  25th,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

The  Full  Engineers'  Transit  that  I  bought  of  you  on  July  28, 
1895,  has  proven  so  satisfactory  to  my  assistant  engineer,  Mr.  J.  I. 
Osborn,  (who  has  been  with  me  for  12  years)  and  myself,  that  the 
best  recommendation  I  can  give  for  the  instrument  is  to  say^  that 
you  can  send  me  a  Light  Mountain  Transit,  No.  A 1508,  with  the 
same  fixtures  and  attachments  that  I  have  on  the  other.  •  This 
instrument  is  to  be  used  in  the  city  of  Ansonia,  Conn.,  where  I 
am  the  City  Engineer. 

Yours  very  truly, 
(Signed)  DAVID  C.  SANFORD, 

Engineer  for  Shell  Fish  Co. 


QUEEN   &  CO.,   INC.,   PHILADELPHIA.  153 

(Copy.) 
COATESVILLE,  PA.,  Feb.  2d,   1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
RESPECTFULLY : — 

Replying  to  your  favor  of  24th,  regarding  the  Surveyors'  Tran- 
sit, No.  A 1502,  shipped  us  September  25th,  1894,  would  say  it  has 
been  very  satisfactory,  and  we  have  had  considerable  work  to  do 
with  it  in  connection  with  the  many  extensions  and  improvements 
we  have  been  doing  around  our  works,  and  we  gladly  give  our 
testimonial  to  you  in  this  connection. 

Yours,  etc., 
LUKENS  IRON  &  STEEL  CO., 

(Signed)  H.  B.  SPACKMAN, 

Purchasing  Agent. 


(Copy.) 

Woodside  Hospital. 

KANE,  PA.,  Feb.  23d,   1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  :— 

I  am  well  pleased  with 'the  Surveyors'  Transit,  No.  A 1502,  that 
I  bought  from  you  last  April.  I  find  it  a  very  serviceable  and  accur- 
ate transit  so  far  and  it  seems  as  good  as  new. 

Yours  truly, 
(Signed)  DR.  THOMAS  L.  KANE. 


(Copy.) 

PITXSTON,  PA.,  March  ist,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

Yours  of  February  i9th  at  hand,  and  in  reply  would  cheer- 
fully say  that  the  Transit  purchased  of  you  April  2oth,  1896,  is 
giving  the  best  of  satisfaction.  I  would  not  know  how  to  get  along 
without  it.  Have  found  it  correct  and  reliable  and  the  workman- 
ship is  second  to  none. 

Very  truly  yours, 
(Signed)  B.  GRIFFEN, 

Arichitect  and  Builder. 


154  QUEEN  &  CO.,   INC.,  PHILADELPHIA. 

(Copy.) 

HASTINGS,  PA.,  March  8th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

We  take  pleasure  in  recommending  the  Light  Mountain  Tran^ 
sit,  No.  A 1 508,  shipped  us  by  your  company.  After  a  thorough 
trial  we  have  found  it  perfect  in  every  detail. 

Yours  truly, 

BENTONCOALCO., 
(Signed)  J.  HALLPORT, 

Superintendent. 

(Copy.) 

City  of  New  York, 

Commissioner  of  Street  Improvements. 

HIGHBRIDGE,  N.  Y;,  February  26th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

I  take  pleasure  in  acknowledging  that  I  am  greatly  pleased' 
with  the  Full  Engineers'  Transit,  No.  A 1494,  which  you  made  for 
me.  I  have  found  it  to  be  satisfactory  in  all  its  requirements,  and  I 
am  sure  that  it  is  a  thoroughly  well  made  and  accurate  instrument.. 

Respectfully, 
(Signed)  JAS.  H.  MALONEY, 

Civil  Engineer  and  City  Surveyor. 


(Copy.) 
The  Freeman    Wilson  Coal  Co. 

HOUTZDALE,  PA.,  March  5th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

Your  letter  of  the  26th  ult.,  received.  In  reply  will  say  that 
I  can  cheerfully  recommend  for  accurate  work  the  transit  I  pur- 
chased from  you  January  yth,  1894. 

Yours  truly, 
(Signed)  JOHN  QUINN, 

Supt.  C.  E.  and  M.  E. 


QUEEN  &  CO.,  INC.,  PHILADELPHIA.  J55 

(Copy.) 
The  Freeman  Wilson  Coal  Co. 

HOUTZDALE,  PA.,  March  25th,   1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

In  recommending  your  Surveyors'  Transit  in  my  letter  of  the 
3th  inst.  I  should  have  informed  you  that  in  making  a  survey 
•with  it,  I  was  so  fortunate  as  to  make  two  drill  holes  meet. 

When  locating  an  air  shaft  to  the  Freeman  Wilson  Coal  Go's, 
mine,  at  Bear  Run,  it  was  found  necessary  to  put  down  a  drill  hole 
to  drain  off  the  water.  I  made  "one"  accurate  survey  in  the 
mine,  and  stamped  a  hole  in  the  roof  directly  under  the  drill  hole, 
according  to  our  measurements,  to  drill  up  and  meet  the  drill  hole 
coming  down.  I  was  surprised  when  the  top  drill  dropped  down 
through  the  hole  I  had  started  from  the  bottom,  I  did  not  expect  it 
to  be  so  accurate.  I  might  also  state  that  the  heading  driven  under 
the  shaft  came  square  with  the  sides  of  the  shaft. 

Yours  truly, 
(Signed)  JOHN  QUINN. 


(Copy.) 
The  Colorado  Fuel  and  Iron  Co. 

DENVER,  COL.,  March  loth,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS  : — 

The  Light  Mountain  Transit,  No.  A 1508,  received  from  you  in 
July,  1894,  has  been  in  constant  service  ever  since.  It  has  been 
used  in  the  surveys  of  iron  mines,  for  surface  work  in  running  out 
section  lines  and  in  coal  mine  surveys,  where  it  has  been  subjected 
to  great  extremes  of  temperature,  moisture  and  dryness.  It  has  given 
the  best  of  satisfaction,  has  held  its  adjustments  well  and  with  the 
diagonal  prism  and  eye  piece  has  enabled  most  satisfactory  solar 
observations  to  be  made. 

With  careful  handling  we  have  made  some  fine  "  closes,"  both 
in  vertical  and  horizontal  angle  work,  of  four  or  five  miles  of  line. 
J  think  it  a  first-class  instrument. 

Yours  truly, 
(Signed)  R.  M.  HOSEA, 

Chief  Engineer. 


156  QUEEN   &  CO.,   INC.,   PHILADELPHIA. 

(Copy.) 
Midland  Sampling  and  Cre  Co. 

CRIPPLE  CREEK,  COLO.,  March  9th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

Your  favor  of  2d  at  hand  and  fully  noted.  The  Light  Mount- 
ain Transit,  No.  A 1 508,  of  your  make  shipped  me  on  August  31, 
1894,  including  the  Vertical  Telescope  and  Solar  Attachment  is  the 
most  complete  and  accurate  instrument  I  have  ever  used,  after  an 
experience  of  twenty  years  in  mining  engineering  and  general 
metallurgical  constructions,  etc.  You  are  at  liberty  to  so  state  over 
my  signature. 

Yours  truly, 

(Signed)  J.  P.  MURRAY,  E.  M. 

P.  S.  You  are  also  at  liberty  to  use  our  Mr.  G.  G.  Moore's 
name  as  to  the  merits  of  your  instrument. 

(Signed)  W.  G.  MOORE,  M.  E- 


(Copy.) 
/.  L.  Rumbarger  Lumber  Co. 

DOBBIN,  W.  VA.,  March  29th,  1897. 
QUEEN  &  Co.,  INC., 
GENTLEMEN : — 

I  take  pleasure  in  saying  that  the  Full  Engineers'  Transit,  No. 
A  1494,  and  Engineers'  Y  Level,  No.  Ai528,  bought  by  the  J.  L. 
Bumbarger  Lumber  Co.  in  1895,  and  used  by  myself  in  constructing 
a  road  for  the  same  company,  were  the  best  I  have  ever  had  the 
pleasure  of  using.  The  transit  may  have  an  equal,  but  no  superior. 
I  ran  seven  miles  of  levels  and  check  levels  with  the  level  which 
you  shipped  the  said  company,  and  checked  out  on  my  bench  mark, 
at  the  end  of  the  seven  miles,  a  little  less  than  2-10.  This  instru- 
ment has  never  been  adjusted  from  the  time  we  got  it  uptto  the 
time  I  made  this  check. 

I  take  great  pleasure  in  recommending  your  instruments  to  the 
use  of  any  parties  who  are  in  need  of  a  first-class  set  of  instruments. 

Yours  very  truly, 
(Signed)  D.  R.  SHULL, 

Engineer  in  charge  of  construction  on 

road  for  J.  L.  Rumbarger  Lumber  Co. 


QUEEN  &  CO.,  INC.,  PHILADELPHIA.  157 

(Copy.) 
2550  N.  8th  St.  PHILADELPHIA,  PA.,  March  3d,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS  — 

In  answer  to  your  request,  I  will  say  that  I  am  perfectly  satis- 
fied with  the  Reconnoissance  Transit,  No.  A  1518,  which  I  purchased 
from  you  March  i3th,  1895,  for  I  have  made  the  cost  of  the  same  in 
three  months  by  saving  time.  Will  soon  call  for  one  of  your  finer 

instruments. 

Respectfully  yours, 

(Signed)  JOHN  E.  HEVENER, 

Carpenter  and  Builder. 


(Copy.) 
204.3  Westmoreland  St.  PHILADELPHIA,  March  6th,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN • — 

The  Reconnoissance  Transit,  No.  A  1518,  we  bought  of  you  on 
the  1 4th  of  August,  1895,  has  been  in  constant  use  ever  since,  and 
has  proven  perfectly  satisfactory  and  reliable  in  every  particular,  and 
we  take  pleasure  in  recommending  your  instruments  to  anyone  need- 
ing a  reliable  transit. 

Respectfully  yours, 

(Signed)  WRIGHT  &  PRENTZEL, 

Builders  and  Contractors. 


(Copy.) 

"  PERTH  AM  BOY,  N.  J.,  March  6th,  1897. 
QUEEN  &  Co.,  fore., 
GENTLEMEN : — 

In  reply  to  your  letter  of  March  3d,  we  wish  to  say  that  the 
Engineers'  Transit,  No.  A 1494,  which  we  purchased  from  you  some 
time  since  has  given  us  the  very  best  of  satisfaction,  and  it  affords 
us  great  pleasure  to  testify  to  its  good  qualities. 
Yours  truly, 

THE  C.  PARDEE  WORKS, 

(Signed)  F.  S.  CHAPIN, 

Treasurer. 


I58  QUEEN  &  CO.,  INC.,   PHILADELPHIA. 

(Copy.) 

Miami  University. 

OXFORD,  O.,  March  i3th,  1897 
MESSRS.  QUEEN  &  Co..  INC., 
DEAR  SIRS  : — 

I  have  your  inqury  of  Feb.  iQth,  relative  to  your  Engineers' 
Transit,  No.  A 1502,  which  we  bought  last  summer.  In  so  far  as 
we  have  had  occasion  to  use  it,  we  find  it  very convienent  and  quick 
to  handle,  and  very  accurate.  It  is  also  neat  and  well  made. 

Yours  very  truly, 
(Signed)  E.  P.  THOMPSON,  A.  M., 

Prof.  Mathematics. 


(Copy.) 

CHICAGO,  ILL.,  Feb.  22d,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

Replying  to  your  letter  of  the  1 9th  hist.,  will  say  that  the 
engineering  instrument  we  bought  from  you  has  proved  entirely 
satisfactory. 

Respectfully  yours, 
(Signed)  L.  L.  LEACH  &  SON, 

Builders  and  General  Contractors. 


(Copy.) 
International  Cooling  Co. 

32  Pine  Street.  NEW  YORK,  Feb.  26th,  1897, 

MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  : — 

Replying  to  your  favor  of  Feb.  25th,  we  purchased  one  of  your 
Improved  Engineers'  Y  Levels  in  April,  1895,  and  have  been  t^ing 
it  in  establishing  very  small  grades  and  exact  levels  in  laying  our 
street  pipe  lines.  We  have  found  it  a  perfect  instrument  for  this 
purpose  entirely  satisfactory  in  every  way. 

Yours  very  truly, 
INTERNATIONAL  COOLING  COMPANY, 

(Signed)  J.  E.  STARR, 

Chief  Engineer. 


QUEEN  &  CO.,  INC.,.  PHILADELPHIA.  159 

(Copy.) 

SPARTANSBURG,  S.  C.,  Feb.  27th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
•GENTLEMEN  : — 

It  is  with  great  pleasure  we  add  our  testimony  in  regard  to  the 
quality  of  your  instruments,  field  and  office. 

We  have  some  small  office  instruments,  made  by  "Queen," 
in  daily  use,  which  were  purchased  by  our  grandfather  in  the  fifties. 
The  Full  Engineers'  Transit,  No.  A 1494,  purchased  of  you  in 
June,  1895,  proved  to  be  a  most  excellent  instrument.  The  limb 
especially,  which  was  put  to  severe  tests  by  our  work,  was  used 
with  great  confidence  and  satisfaction .  The  centering  and  gradua- 
tions were  perfect  beyond  our  ability  to  discover  error.  We  could 
write  a  long  letter,  in  this  strain,  descriptive  of  other  parts  of  this 
instrument. 

Very  respectfully  yours, 
(Signed)  LADSHAW  &  LADSHAW, 

Civil  and  Hydraulic  Engineers. 


(Copy.) 

NINETY-SIX,  S.  C.,  May  ist,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
•GENTLEMEN  : — 

The  Builders'  Transit  purchased  irom  your  agent,  Mr.  H.  W. 
Johnson,  of  Greenwood,  S.  C.,  has  given  perfect  satisfaction.  I 
decided  to  buy  this  instrument  after  correspondence  with  about  a 
dozen  of  the  best  makers  in  the  United  States,  and  I  do  not  hesitate 
to  say  that  it  is,  in  my  opinion,  the  best  instrument  on  the  market 
for  $100.00.  I  was  a  little  uneasy  lest  I  should  get  an  inferior  tele- 
scope; but  can  say  that  my  telescope  shows  a  clear,  well-lighted 
image,  sufficiently  magnified  for  all  purposes  of  the  surveyor. 

After  a  year's  thorough  trial  it  has  won  my  confidence  and 
respect  as  a  faithful   and   reliable   companion.      It   is   admirably 
adapted  where  local  attraction  abounds  as  it  does  in  my  vicinity. 
Very  respectfully  yours, 
(Signed)  THOS.  C.  ANDERSON. 


I6o  QUEEN  &  CO.,   INC.,   PHILADELPHIA. 

(Copy.) 
2i8N.i3ihSt.  PHILADELPHIA,  PA.,  March  4th,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN: — 

We  have  had  one  of  your  Surveyors'  Transits,  No.  A 1502,  in 
use  for  the  past  two  years  and  have  found  it  perfectly  accurate  and 
satisfactory. 

Very  respectfully  yours, 

(Signed)  R.  C.  BALLINGER  &  CO., 

Contractors  and  Builders. 


(Copy.) 
Equitable  Building.  BALTIMORE,  MD.,  March  4th,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  :— 

Replying  to  your  favor  of  the  2d  inst. ,  would  say  that  all  the 
instruments  which  we  have  purchased  from  you  we  have  never  had 
a  fault  to  find,  as  they  have  been  accurate,  practical,  best  finish  and 
workmanship. 

Wishing  you  a  successful  future,  we  are 
Yours  very  truly, 

CAMPBELL  &  ZELL  CO., 

Engineers  and  Founders. 


(Copy.) 

KREBS,  IND.  TER.,  March  8th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN  :—  ^ 

We  have  owned  and  used  a  set  of  your  engineering  instru> 
ments,  including  Full  Engineers'  Transit,  No.  Ai5O2,  and  Engi- 
neers' Y  Level,  No.  A 1528,  for  the  past  eighteen  months,  and  it 
affords  us  pleasure  to  recommend  them  to  any  one  desiring  to  use 
first-class  engineering  instruments. 

Very  truly, 
(Signed)  T.  J.  PHILLIPS  &  CO. 


QUEEN   &   CO.,   INC.,   PHILADELPHIA.  161 

(Copy.) 

DAVIDSON  COLLEGE,  N.  C.,  March  gth,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 

GENTLEMEN  : — 

In  reply  to  your  recent  letter  it  gives  me  pleasure  to  state  that  the 
£econnoissance  Transit,  No.  A  1518,  which  the  college  bought  from 
you  three  years  ago,  has  given  entire  satisfaction  in  every  respect. 

Yours  truly, 
(Signed)         W.  D.  VINSON,  M.  A.,  LL.  D. 

Professor  Mathematics. 


(Copy.) 
No.  70  Kilby  St.  BOSTON,  MASS.,  February  23d,  1897. 

MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS  : — 

Replying  to  yours  of  the  i9th  requesting  our  opinion  of  the 
combined  Transit  and  Level,  No.  A 1494,  which  you  shipped 
us  on  January  28th,  1896,  would  say  that  we  did  not  give  this 
instrument  any  great  amount  of  use,  as  it  was  destroyed  in  the 
fire  which  we  had  at  our  works  last  Fall,  but  from  the  use  which  we 
did  give  it,  we  found  it  to  be  a  very  satisfactory  instrument,  exceed- 
ingly light  and  portable. 

Yours  truly, 

BOSTON  BRIDGE  WORKS, 
(Signed)  R.  N.  BROWN, 

Chief  Engineer. 

ARDMORE,  PA.,  March  loth,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
DEAR  SIRS:— 

The  Architects'  Level,  No.  A 1532,  received  from  you  a  year  ago 
has  given  me  great  satisfaction.  It  has  never  been  out  of  order,  or 
required  adjustment  so  far,  although  we  have  done  a  great  deal  01 
with  it. 

Yours  truly, 
(Signed)  EDWARD  CAMPBELL, 

Landscape  Architect. 


162  QUEEN  &  CO.,   INC.,  PHILADELPHIA. 

(Copy.) 
The  Pusey  &  Jones  Co. 

WILMINGTON,  DEL.,  February  24th,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
OENTLEMEN  : — 

I  purchased  one  of  your  Improved  i8-in.  Engineers'  Y  Levels 
•early  in  the  year  1896  and  have  used  it  on  many  occasions. 

It  affords  me  pleasure  to  state  that  this  instrument  has  been 
very  satisfactory  in  every  respect. 

Yours  truly, 
.       (Signed)  T.  H.  SAVKRY,  V.  P. 


(Copy.) 

SALEM,  MASS.,  March  2d,  1897. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN : — 

In  reply  to  yours  in  regard  to  the  i8-in.  Engineers'  Y  Level, 
would  say  that  I  like  it  very  much.  It  is  neat,  light,  handy,  and 
has  excellent  lenses.  Anyone  wanting  such  an  instrument  I  should 
certainly  recommend  your  make. 

Very  truly, 
(Signed)  JOS.  C.  FOSTER. 


(Copy.) 

Grandview  Cemetery  Co. 

WILLIAMSPORT,  PA.,  March  5th,  1807. 
MESSRS.  QUEEN  &  Co.,  INC., 
GENTLEMEN: — 

The  Architects'  Level,  No.  A 1532,  purchased  of  you  has  given 
entire  satisfaction,  the  adjustment  and  finish  being  perfect  and  its 
work  accurate. 

Yours  truly, 

(Signed)  J.  W.  MUSSINA. 


INDEX. 

PAGE. 

Alt-Azimuth 18,  19 

Architects'  Levels 60,  61,  62- 

Alt-Azimuth  (Pocket 97 

Artificial  Horizon 98 

Anisler  Planimeter 98 

Angle  Mirrors IOI 

Aneroid  Barometers in,  112,  113 

Anemometers 114,  115 

Builders'  Transits 52,  53 

City  and  Bridge  Transits 20,  21,  22,  23,  24 

Clinometers 94,  95 

Cross  Staff  Heads     .    . .   .  * ,  .   .   .    100 

Chains 109. 

Diagonal  Prisms       67 

Engineers' Transits 28,29,30,31,32,33,34,35 

Engineers'  Y  Levels 58,  59 

Explorers'  Transit 25 

Extras  and  Parts  .   .  .  .  • 63,  64,  65,  66,  67,  68,  69 

Gradienter 64 

Geologists'  Compasses 81 

Hand  Levels 92,  93 

Heliograph 97 

Light  Mountain  Transits 42,  43,  44,  45,  46,  47,  48,  49 

Land  Levels 63 

Machininists'  Levels 95 

Marking  Pins no 

Magnifying  Glasses     .   .   .  «, '. 116 

Odometers 102 

Plane  Tables 54,55 

Precision  Levels 56,  57 

Plummet  Lamps 67 

Pocket  Compasses 77,  78,  79 

Prismatic  Compasses 82,  83,  84 

Pedometers IOI,  102 

Plumb  Bobs no 

Reconnoissance  Transit 50,  51 

Reflectors 67 

Repair  Work 71 

Rods 72,  73,  74,  75 

Reflecting  Mirrors 100 

Rectangular  Prisms •   •    .   .   .    100 

Surveyors'  Transits     .   .  * 36,  37,  38,  49,  40,  41 

Solar  Attachment 6tf 

Side  Telescopes    .   .  ;_ 66,  67f 

Spirit  Levels      .  -. TO 

Sight  Compasses 80 

Surveyors'  Pocket  Compasses 85 

Surveyors'  Compasses 86,  87,  88,  89,  90,  91 

Sextants      96,  97 

Stake  Tacks no 

Scientific  Books 119  to  142 

Transit  Theodolite 16,  17 

Tripods 76 

Tapes 103,  104,  105,  106,  107,  108 

Time  Charts 117,  "* 

Tilting  Level 61 

Tunnel  Transits 26,  27 

Vernier  Attachment.  65 


WE  PUBLISH  PRICED  AND  ILLUSTRATED  CATALOGUES 

As  follows,  any  or  all  of  which  will  be  mailed  on  receipt  of  price : 
Catalogue  Mathematical. 

Containing  Drawing  Instruments,  Protractors,  Scales,  Calculating  Instruments,  Planimeters,  Tri- 
angles, T  Squares,  Curves,  Rulers,  Drawing  Boards,  Drawing,  Tracing  and  Profile  Papers,  Erasers, 
Pens,  Pencils,  Ink,  etc.  Price,  20  cents. 

Catalogue  Engineering. 

Containing  Transits,  levels,  Compasses,  Rods,  Tapes,  Scientific  Books,  etc.    Price,  15  cents. 

Catalogue  B. — Microscopical  Instruments,  108  pages. 

Contains  list  and  prices  of  Reading-glasses,  Simple  Microscopes,  Compound  Microscopes,  Microscopic 
Objectives  and  Accessories,  Mounting  Materials,  Microscopic  Objects  (including  Histological  and 
*  Pathological  Specimens),  Works  upon  Microscopy,  Graphoscopes,,  Stereoscope,  etc.,  etc.     Price,  35 
cents. 

Catalogue  C. — Second-Hand  Microscopes,  Accessories,  etc.,  16  pages. 

Catalogue  D. — Ophthalmological  Instruments,  125  pages. 

Contains  description  and  prices  of  all  good  forms  of  Spectacles  and  Eye-glasses,  with  copious  explana- 
tions, Models  of  the  Eye,  Artificial  Eyes,  Ophthalmoscopes,  Phakometers,  Optometers,  Trial  Sets, 
Trial  Frames,  Test  Cards,  Color  Tests,  Works  upon  the  Eye,  etc.,  etc.  Price,  20  cents. 

Catalogue  E. — Spectacles  and  Eye-Glasses,  75  pages. 

Contains  description  and  prices  of  all  the  latest  styles  of  Spectacles  and  Eye-Glasses,  Lorgnettes,  Eye* 
Glass  Chains,  Hooks,  Cases,  etc.  Price,  10  cents. 

How  to  Fit  Glasses,  112  pages. 

A  Manual  for  the  use  of  Opticians,  Jewelers,  Druggists  and  others  who  sell  Spectacles  and  Eye- 
Glasses.  It  is  concisely  and  plainly  written,  with  illustrated  cases.  A  supplement  contains  list  of 
such  goods  as  dealers  in  glasses  would  require.  The  whole  is  indispensable  to  one  who  wishes  to  be- 
come an  Optician,  and  is  also  replete  with  information  of  great  value  to  one  who  is  already  familiar 
with  the  optical  trade.  Profusely  illustrated.  Price,  75  cents. 

Catalogue  F. — Opera-Glasses,  Tourists^  Glasses,  Race-Glasses.  Field-Glasses    and  Spy- 
Glasses,  43  pages.     Price,  10  cents. 

Catalogue  G. — Astronomical  Telescopes  and  Appliances^  36  pages.     Price,  8  cents. 

Catalogue  H. — Projecting  Lanterns  and  Views,  132  pages. 

Contains  list  and  prices  of  Lanterns  for  Public  and  Private  Exhibitions,  Sciopticons,  Stereopticons, 
Scientific  Lanterns,  and  accessory  apparatus  to  be  used  with  them;  Lantern  Slides  of  all  descrip- 
tions. Price,  15  cents. 

Catalogue  I. — Physical  Instruments,  255  pages. 

Contains  list  and  prices  of  instruments  to  illustrate  lectures  in  every  department  of  Physics  and 
Chemical  Science,  Air  Pumps,  Electric  Machines,  Galvanic  Batteries,  Globes,  Auzoux's  Anatomical 
Models,  and  books  relating  to  Scientific  Subjects.  Price,  40  cents. 

Catalogue  I,  No.  46. — Physical  Optics,  30  pages.     Price,  6  cents. 
Catalogue  K. — Chemicals,  48  pages.     Price,  6  cents. 
Catalogue  N. — Meteorological  Instruments,  127  pages. 

Contains  lists  and  prices  of  Thermometers,  Mercurial  and  Aneroid  Barometers,  Hygrometers,  Ane- 
mometers, Rain  Gauges,  Wind  Gauges,  Tide  Gauges,  Current  Meters,  Pyrometers,  Hydrometer, 
Salinometers,  Vacuumeters,  Water  Gauges,  Miners'  Safety  Lamps,  Pressure  and  Vaccuum  Gauges, 
and  all  instruments  for  measuring  Steam,  Air,  Gas  or  Water.  Price,  12  cents. 

Catalogue  O  and  P. — Photographic  Apparatus,  140  pages. 

Including  Cameras,  Lenses,  Dry  Plates  and  Photographic  Supplies.    Price,  12  cents. 

Catalogue  S. — Chemical  Apparatus,  375  pages. 

Contains  list  and  prices  of  Apparatus  as  used  in  every  department  of  Chemistry.    Price,  50  cents. 

Catalogue  X. — Electrical  Test  Instruments,  72  pages.     Price,  10  cents. 
Catalogue  221. — Anatomical  Models,  24  pages.     Price,  6  cents. 

The  price  of  any  of  our  single  Catalogues  will  be  deducted  from  the  first  order  amounting  to  $10.  We  will 

bind  all  our  Catalogues  mentioned  above  in  cloth  with  leather  back,  and 

mail  the  complete  book  to  any  address  for  $3.50. 

QUEEN  &  CO., 

Mathematical,  Optical  and  Philosophical  Instruments, 
1010  Chestnut  Street,  Philadelphia. 


THE  HOUSE  ...OP... 

QUEEN  &  Co.,  inc. 

Was  established  in  1853  and  REORGANIZED  in  1896, 
and  consists  of  the  following  Sales  Departments  : 

Optical  Department, 

comprising  Optical  and  Ophthalmological  Instruments,  and  Field  and 
Opera  Glasses. 
Mathematical  and  Engineering  Department, 

comprising  Drawing  Instruments  and  Materials,  and  Engineering  and 
Surveying  Instruments. 

Microscopical  Department, 

comprising  Microscopes  ; Magnifiers,  and  Botanical  and  Bacteriological 
Supplies. 

Physical  and  Electrical  Department, 

comprising  Physical  and  Electrical  Instruments  and  Apparatus,  X-Ray 
Apparatus  and  Anatomical  Models. 

Astronomical  and  Projection  Department, 

comprising  Projection  Apparatus,  Astronomical  Telescopes  and  Polar- 
izing Apparatus. 

Meteorological  Department, 

comprising  Meteorological  Instruments,  Barometers  and  Thermometers 
and  Pyrometers  for  physical  and  technical  use. 

Photographic  Department, 

comprising  Cameras  and  Lenses,  and  Photographic  Supplies  in  general. 

Chemical  Department, 

comprising  Chemicals  and  Chemical  Apparatus  and  Fine  Balances. 

These  Sales  Departments  depend  principally  upon  our  WELL 
EQUIPPED  FACTORIES,  of  which  we  maintain  the  following  : 

Physical,  Electrical  and  Engineering  Instrument  Factory, 

Optical  Factory, 

Thermometer  and  Chemical  Glassware  Factory, 
Electrical  Laboratory,  Wood  Working  Factory. 

Each  of  our  Sales  and  Manufacturing  Departments  is  under  a  competent  manager, 
with  whom  is  associated  an  able  corps  of  assistants,  many  of  whom  are  recognized  experts 
in  their  special  lines. 

Jn  addition  to  our  own  products,  we  represent  a  number  of  well-known  foreign 
houses  about  whose  apparatus,  which  we  can  supply,  either  from  stock  or  import  duty 
free  for  institutions,  we  are  at  all  times  prepared  to  give  information. 

M.OGUE  and  CIRCULARS  of  any  of  the  departments  will  be  sent  free  by  mail  upon 
application. 

QUEEN  &  CO.,  Inc. 

ioio  Chestnut  Street 

NEW  YORK  BRANCH,  59  Fifth  Avenue  PHILADELPHIA 


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................................................................................ ,...„. 


"QUEEN"  FULL  ENGINEERS'  TRANSIT. 


! 


14  DAY  USE 


RETURN  TQ 


RROWED 


This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


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